The proceedings of this workshop are available here.
Transcription
The proceedings of this workshop are available here.
Proceedings of 66Bi-isotropicstgS " Workshop on novel microwave materials Ari Sihvola (editor) Eelsinki University of Technology Faculty of Electrical Engineering Electtomagnetics Laboratory Otalaari 5 A, SF-02150Espoo,Finland Report 137 I'c r ,Ifi.!'y L993 Proceedings of ,,Bi-isotropics,g3,, Workshop on novel microwave materials Ari Sihvola(ed.itor) Report 132 February19g3 Abstract R:.'rliJH,T.J;;1 ofrebruarytee3,the,Workshop Bi_isotropzcs,es of rechnologyin Finland. washeld at rrr" t"pi..irf," .t""rro*u*n.;;";;'t ,,oo...iprJ.u.l;;;;':-**t:towave wasthe engineerinsaspects of novel mat "r*,,ng ,u*'"u"i",,,"a.,i*'.*H;#ru*"*;i1tiffi j4#ilJ*ii*l; r,r,Ttr ISBN 951_22_1442_3 ISSN0784_848X TKK OFFSET Table of contents Introduction Workshopprogramme List of participants 7 q Selectedbibliography 11 Ismo Lindell: Electromagneticsin novel isotropic media 2t Ari Sihvola: Dictionary between different definitions of bi-isotropic material parameters 33 Fr6d6ric Maiotte: Theory of guided waves in chiral media: a step for measuring chiral material parameters 47 Arto Hujanen: Measuring electrical, magnetic, and chiral material parameters 43 Luk R. Arnaut and .Lione/E. Davis: Electromagnetic properties of losslessn-turn helices in the quasi-stationary approximation 57 Ismo Lindell and Ari Viitanen: Plane wave propagation in a uniaxial bianisotropic medium 61 Ari Viitanen and Ismo Lindell: Plane wavepropagation in a uniaxial bianisotropic medium with an application to a polarization transformer 63 Ismo Lindell, Ari Viitanen, and Pdivi Koivisto: Plane-wavepropagation in a transversely bianisotropic uniaxial medium 65 SergeiA. Tretyakov and Alexander A. Sochava:Novel uniaxial bianisotropic materials 67 Ari Sihvola: Macroscopicpredictions of material parameters for heterogeneousbi media 7T FedorI. Fedorov: Covariant methods in the theory of electromagneticwaves 7s Anatoly N. Serdyukov.' Fundamental principles restricting the macroscopicphenomenological description of matter 77 Igor V. SemcJrenko;Particular wavesin bi-isotropic media gs Introduction Electromagneticsand microwavetechnology are progressingthese years with considerable pace. One of the frontiers at which major conquests are being made is that of new materials. The interaction of electric and magnetic fields with matter is determined by the physical phenomenataking place within media, but in the electromagnetic description, these effects are reduced to plain material parameters that expressthe magnitua. of tt responsebetween the exciting field and the correspondingpolarization. It is only during" the latest years that microwave community has recognizlJ the potentinl of norn"l,mo.I complicated material effectsin the design of new componentsani systems. Complex materials have, indeed, attracted the attention of severalresearchgroups working in the electromagnetics,microwave,millimeter wave, and optical areas. The classof these media - upon which sometimesthe label "exotictt is attached - contains several types of materials that loosely can be said to have one thing in common: the ability to some special efect when excited by the electromagneticwave. As "*tibit examplesbe mentoined chiral, nonreciprocal, nonlinear, gyrotropic, anisotropic, high-?i superconducting, etc., materials, all of which promise applications in microwave "r,girr"".irrg. Bi-isotropic media are a subgroup of these novel materials. These are isotropic, i.e. they behavesimilarly regardlessthe direction of the vector force of the electric or magnetic fieli. But they are 6i-isotropic, meaning that there is electrically incited magnetic polarization and vice versa. one might divide bi-isotropic materials in five groups: c dielectric media, consistingmicroscopicallyof electrically polarizable entities, which are induced by the electric field c rnagnetic media, displaying analogously magnetic polarization due to an external magnetic field r reciprocal chiral mediu that due to their inherent left- or right-handednessexhibit magnetically caused electric dipole moment density and vice versa; these are also called Pasteur media o nonreciprocalmedia, where the magnetoelectric effect is cophasal unlike in chiral media; also called as Tellegen media o media characterizedby any combination of these four efiects In the beginning of February, 1993, Helsinki University of Technology hosted a workshop on novel microwave materials. Bi-isotropicsSS was the name of tie four-day-and-nighi workshop that attracted 17 participants from six countries: Finland, Russia, BelorrrrJiu. France, United Kingdom, and Germany. The focus of the talks was intended to be the theory and applications of bi-isotropic materials in electromagneticsand microwave engineering,but it may be the nature of this rapidly progressingfield a reasonfor the fact that also results on more general,bianisotropic materials were discussed(not to mention the informal interaction sessionswhere topics like scientific ethics and turmoils in global political structures were reached). Perhaps even Bianisotropics'9? would be too narrow a title for the next workshop to follow. - Someform of continuation io Bi-isotropics'9? will certainly materialize; the desire is evident. This report is a compilation of written material from the presentationsheld during the ttbook of abstracts" are diverse: the contributions range workshop. The pages of this from full reports through short summariesto copiesof the viewgraphs shown in the oral presentation. Without apologizing for this type of formal shortcomingsof my collection, I hope that the information about researchresults - especiallyby workshop participants from the former Soviet Union - will percolate on the pages of this report through the electromagneticsand microwave communities of our world. * Bringing together participants from various countries, and especially from economically unequally-equippedsocieties,requirescommitment in terms of money. I wish to acknowledge the financial assistancefrom the following three agencies: o IEEE (The Institute of Electricaland ElectronicsEngineers)MTT (MicrowaveTheory and Techniques)Society within Region 8 o URSI (InternationalUnion of Radio Science)Finnish National Committee o The ElectromagneticsLaboratory of Eelsinki University of Technology St. Valentine'sDay, 1993 Ari Sihvola, Workshop Organizer Bi-isotropics Elec_trom_agnetics of Novel Microwave Materials Workshop in Espoo, Finland, L_4 February lggg F I N A LP R O G R A M M E i Monday, I February 9.00 Ari Sihvola (Helsinki University of Technology,Finland) Welcome and opening of the workshop 9.30 Ismo Lindell (Helsinki University of Technology,Finland) Introduction to electromagneticsin novel bi-isotropic med.ia 11 .00 Discussion 1 1 . 3 0L u n c h 13.00 Ari Sihvola (Eelsinki University of Technology,Finland) Constitutive relations in bi-isotropic desciption 13.30 Fr6d6ricMariotte (C.E.S.T.A., France) and Nader Engheta (University of pennsylvania, USA) Theory of guided wavespropagation in chiral media: a step for measuring chiral material parameters 14.30 Discussion 15.30 Arto Hujanen (State TechnicalResearchCentre,Finland) Measuring electric, magnetic, and chiral materiar param"t..s 16'00 sergei rretyakov (st. petersburg state Technical universitv. Russia) Comment on bi-slab measurementpossibilities 16.30 Discussion I\resday, 2 February 9.00 Luk Arnaut (Manchester,United Kingdom,l Microwave chiral researchat the UMIST 9 .45 Discussion 10.15 Ismo Lindell (Eelsinki University of Technology,Finland) Theory of wave propagation in uniaxial bianisotropicmedium 1 , t l E Discussion 1 1. 3 0 Ari Viitanen (Helsinki University of Technology,Finland) Numerical examplesof wave propagation in uniaxiar bianisotropic medium 7 2 . L 5Discussion 1 2 . 3 0Lunch 1 4 . 3 0Sergei Tretyakov (St. Petersburg State Technical University, Russia) Novel uniaxial pseudochiral materials 1 5. 3 0 Discussion Wednesday, 3 February 9.00 SergeiTretyakov (St. PetersburgState TechnicalUniversity,Russia) Chiral and bi-isotropic materials in waveguidingapplications 9 .45 Discussion 10.00 Ari Sihvola (Helsinki University of Technology,Finland) Macroscopicpredictions of materials parameters for heterogeneousbi media 10.45 Discussion 11.15 Fyodor Fyodorov (BelorussianAcademyof Sciences,Minsk) Covariant methods in the theory of electromagneticwaves 12 .30 Discussion 13.00Lunch 14.00 Visit to the Telecommunications Laboratory of the State Technical ResearchCentre in Otaniemi Thursdayr 4 February 10.30 Anatoly Serdyukov(Gomel State University,Belorussia) Microwave and optical chiralitv researchat the Gomel State University 1 1. 3 0 D i s c u s s i o n 11.45 Igor Semchenko(Gomel State University,Belorussia) Particular wavesin bi-isotropic media 12 . 30 Discussion 13.00 Closingof the Workshop Bi-isotropics'93 Electromagnetics 'Workshop of Novel Microwave in Espoo, Finland, l-4 Materials February 1993 LISTOF PARTICIPANTS I{ORKSHOP ORGAIIISER: Ari Sihvola Helsinki University of Technologr, ElectromagneticsLaboratory Otakasri 5 A, 02150Espoo, Finland Tel. (358)-0-4 5 l-226 l, Fax ( 358)-0-a 5 7-2267,E-mail ari. [email protected] Luk Arnaut UniversityofManchesterInstitute ofScienceand Technology,DepartmentofElectrical Engineering and Electronics,P.O. Box 88, ManchesterM60 lQD, United Kingdom Tel. (aa)-61-236-331 l, Fax (aa)-61-228-7040 Murat Ermutlu Helsinki University of Technologr, ElectromagneticsLaboratory Otakaari 5 A, 02150Espoo, Finland Tel. ( 358)-0-a51-2260,Fax (358)-0+ 5l-2267, D'mail [email protected] Fedor I. Fedorov ByelorussianAcademyof Sciences, Institute of Physics,Skarynapt. 70,220602Minsk, Byelarus Tel. (7)-(0t72)-346-870(home), 39&559 (office) Arto Eujanen Telecommunications Laboratory, State TechnicalResearchCentre, Otakaari 7 B, 02150 Espoo, Finla.nd Tel. (358)-0-a56-5608,Far (358)-0-455-01 15 Arne F. Jacob TechnischeUniversitit Braunschweig,Institut ltr Hochfrequenztechnil Postfach3329,3300Braunschweig,Germany Tel. (a9)-531-2469, Far (49)-531-391-5841, Dmail i7091001@dbstul Piivi Koivisto Eelsinki University of Technologr, ElectromagneticsLaboratory Otakaari 5 A,02150 Espoo, Finland Tel. (358)-0-45 1-2260,Far (358)-0-4 51-2267,Bmail [email protected] Jukka Lempidinen Helsinki Universityof Technology,ElectromagneticsLabotatory Otakaari 5 A, 02150Espoo, Finland 1-2267 Fax (358)-0-45 Tel. (358)-0-{5r-2260, Ismo Lindell Laboratory Helsinki Universityof Technologl,Electromagnetics Otakaari 5 A, 02150Espoo,Finland Tel. ( 358)-0-a 5l-2266,Fax ( 35s)-0-a 5l-2267,Bmail [email protected] Fr6d6ric Mariotte Commissariati I'llnergie Atomique, C.E.S.T.A.- ServiceSystlme B.P. No, 2, 33114Le Barp, hance Fax (33)-56-s85-121 Tel. (33)-56-684-147, Keijo Nikoskinen Helsinki University of Technologt, ElectromegneticsLaboretory Otakeari 5 A, 02150Espoo,Finland Fax (35S)-0-a5l-2267,Dmail [email protected] Tel. (358)-0-457-2262, Igor V. Semchenko Gomel State University,Departmentof Physics,SovjetskayaStr. 104,246699Gomel, Byelarus Tel. (?)-0232-576-657and 577-520,F-mail dej%[email protected]'eu.net Anatoly N. Serdyukov Gomel State University,Departmentof Physics,SovjetskayaStr. 104,246699Gomel, Byelarus Bmail dej%[email protected] Tel. (7)-0232-563-002, Johan Sten Helsinki Universityof Technologr,ElectromagneticsLaboratory Otakaari 5 A, 02150Espoo,Finland Tel. (358)-0-.451-2260,Fax ( 358)-0-a51-2267,Dmail [email protected] Sergei Tretyakov 29, St. PetersburgState TechnicalUuiversity, Department of Radiophysics,Polytechnicheskaya Russie 195251St. Petersburg, Dmail [email protected] Far (7)-812-552-6086, Tel. (7)-812-552-7685, Ari Viitanen Helsinki Universityof Technology,ElectromagneticsLaboratory Otalaari 5 A, 02150Espoo,Finland Tel. ( 358)-0--a51-2262,Far (358)-0+5 1-2267,Fmail [email protected] Wei Zhang Hclsinli Udversity of Technologr, Radio Laboratoty Otatesri 5 A,02150 Espoo,Finland Tel. (358)-0-45l-2255, Far (358)-0-asL2r52 l0 Selected bibliography l{hat folloes about the j.s a list topi.c electromagnetics exhaustive; in the it of our of and micronave only Electromegnetics publications recent llorkshop: reflects in bianisotropic, applications. tbe range ald journals different especially The domain list of is chiral by literature no means folloced Laboratory. Afonin, A.A., A.N. Godlevskaya, V.N. Kapshai, S.P. Kurlovich, and A.N. Serdyukov: Scattering of electromagnetic waves by a two-Iayer spherical particle in a naturally gyrotropic medium, Oplics anil Spectrcscopg (USSR), Vol. 69, No. 2, p. 242-245, August 1990. Agranovich, V.M., and V.L. Ginzburg: On the phenomenological electrodynamics of gyrotropic media, Journal of Experimenlal and. Theoretical Physics (JETF, I/SS-R/, Vol. 63, No. 3, 1972. Ali, S.M., Habashy, T.M., and Kong, J.A.: Spectral-domain dyadic Gteen's function in layered chiral media, Journal of lhe Opticol Soceily of Americo,.4, Vol. 9, No. 3, p. 473-423, March 1992. Applequist, J.: Optical activity: Biot's bequest, Americon Scienlist, Vol. 75, No. 1, p. 58-68, JanuaryFebruary 1987. Babonas, G., S. Marcinkevidius, and A. Shileike: Structural model of optical activity in semiconductors, Journal of Eleclrmognelic Watsesand Applicatioas, Vol. 6, No. 5/6, p. 573-586, 19g2. Barron, L.D.: Molecular lighl scaltering and oplical acliaity, Cambridge University Press, 1982. Bassiri, S., N. Engheta, and C.H. Papas: Dyadic Green's function end dipole radiation in chiral media, Alla Frequenza, Vol. LV, No. 2, p. 83-88, March-April 1986. Bassiri, S., C.H. Papas, and N. Engheta: Electromagnetic wave propagation through a dielectric-chiral interface and through a chiral slab, Journal of lhe Oplical Society of America A, Vol. 5, No. 9, p. 1 4 5 0 - 1 4 5 9 ,S e p t e m b e r 1 9 8 8 . E r r a t a : V o l . 7 , p . 2 1 5 4 - 2 1 5 5 ,f 9 9 0 . Bhattacharyya, A.K.: Control of radar cross-section and crosspolarization characteristics of an isotropic c h i r a l s p h e r e , E l e c l r o n i c s L e t t e r s , V o l . 2 6 , N o . 1 4 , p . 1 0 6 6 - 1 0 6 ? ,J u l y 1 9 9 0 . Bhattacharyya, A.K., E.K. Miller, and G.J. Burke: Circular loop antenna in unbounded chiral medium: a moment methods solution, Journal of Electromagneiic Watses and, Applicotions, Vol. 6, No. 4, p. 431-44,7992. Bohren, C.F.: Light scattering by an optically active sphere, Chemicol Physics Lellers, Vol. 29, No. 3, p. 458-462,1974. Bohren, C.F.: Scattering of electromagnetic waves by an optically active spherical shell, ?[e Joumal of C h e m i c a l P h y s i c s , V o l . 6 2 , N o . 4 , p . 1 5 6 6 - 1 5 7 1 ,1 9 7 5 . Bokut, B.V., and F.I. Fedorov: Reflection and refraction of light in optically isotropic active medie, O p l i c s a n d S p e c l r c s c o p y( U S S R ) , V o l . 9 , p . 3 3 4 - 3 3 6 , 1 9 6 0 . Bokut, 8.V., A.N. Serdyukov, and F.I. Fedorov: On phenomenological theory of optically active crystals, Kristollogrophiga, Vol. 15, p. 1002-1006, 1970 (in Russian). fEnglish translation in Soo. Phys.Crgslallof .) Bokut,8.V., and A.N. Serdyukov, On the phenomenological theory of optical activity, Journal of Experimentol ond. Theoreticol Physics (JETF, t/55.R/, Vol. 61, No. 5, 1971. Bokut,B.V.,A.N.Serdyukov,andF.I.Fedotov: Formofconstitutiveequationsinopticallyactivecrystals, Optics ond Speclrcscopy (USSR), Vol. 37, No. 2, p. 166-168, August 1974. Bokut, 8.V., A.N. Setdyukov, and V.V. Shepelevich: On the phenomenologicaltheory of absorbing optically ective media, Oplics and Speclrcscopy (USSR), Vol. 37, No. 1, 1974. Bokut, B.V., and A.N. Serdyulov: On the theory of optical activity of non-uniform media, Jorraol of A p p l i e d S p e c t r o s c o p y( U S S R ) , V o l . 2 0 , N o . 4 , p . 6 7 7 - 6 8 1 , 1 9 7 4 ( i n R u s s i a n ) . Chambers, L.G.: Propagation in a gyrational medium, Quarterlg Journol of Mechonics and Applied M a l h e m a l i c s , V o l . 9 , N o . 3 , p . 3 6 0 - 3 7 0 ,1 9 5 6 . Chen, D. and L. Xue: Dipole radiation in the presence of a grounded chirai slab, Miupuare Technologg Lellers, Vol. 5, No. 2, p. 65-68, February 1992. and Oplical Cheng, D. and L. Xue: Dipole radiation in the proximity ofa chiral slab, International Journal of Infiured. and Millimeler Wates, Yol. 12, No. 12, 1991. Cheng, D, W. Lin, and L. Xue: General approach for finding the characteristics of chiral layered media, I n t e r n a l i o n a l J o u r n a l o f I n f i n r e d . o n d .M i l l i m e l e r W o o e s , Y o l . 1 3 , N o . 1 , p . 1 0 5 - 1 1 5 ,J a n u a r y 1 9 9 2 . Cheng, D., J. Cheng, and L. Xue: Radiation of elementary dipole sources in stratified chiral media, Micrpuaae and Oplical Technologg Lellers, Vol. 5, No. 3, p. 135-138, March 1992. Chien, M., Y. Kim, and H. Grebel: Mode conversion in optically active and isotropic waveguides, Oplics L e t t . , Y o l . 1 4 , N o . 1 5 , p . 8 2 6 - 8 2 8 ,1 9 8 9 . Chilo, N.A., and A.N. Serdyukov: Electromagretic wave transmission through a magnetized optically active layer, Journal of Applied, Speclroscopg (USSR), Vol. 25, No.l, p. 169-171 1974 (in Russian). Cloete, J.H. and A.G. Smith: The constitutive parameters of a lossy chiral slab by inversion of plane-wave scattering coefficients, Mictware and Optical Technology Lellers, Vol. 5, No. 7, p. 303-306, June 1992. Condon, E.U.: Theories of optical rotatory power, .Reoieus of Moilern Physics, Vol. October 1937. 9, p. 432-457, Cory, H., and I. Rosenhouse: Electromagnetic wave propagation along a chiral slab, IEE Proceed.ings, Parl H, Vol. 138, No. 1, p. 5l-54, 1991. Cory, H. and T. Tamir: Coupling processesin circular open chirowaveguides, IEE Proceed,ings,Parl E, V o l . 1 3 9 , N o . 2 , p . 1 6 5 - 1 7 0 ,A p r i l 1 9 9 2 . Eftimiu, C., and L.W. Pearson: Guided electromagnetic waves in chiral media,.Radio Science, Vol. 24, N o . 3 , p . 3 5 1 - 3 5 9 ,1 9 8 9 . Elshetbeni, A.2., J. Stanier, and M. Hamid: Eigenvalues of propagating waves in a circular waveguide with an impedance wall, lEE Proceedings .f1,Vol. 135, No. l, p. 23-26, 1988. Engheta, N., and A.R. Michelson: Transition radiation caused by a chiral plate, IEEE Antennas and Prcpogalion, Vol. 30, No. 6, p. 12f3-1216,1982. Itransaclions on Engheta, N., and D.L. Jaggard: Electromagnetic chirality and its applications, IEEE Anlennas and Prcpagotion Sociely Newsleller, Vol. 30, No. 5, p. 6-12, October 1g88. E n g h e t a , N . , a n d P . P e l e t : M o d e s i n c h i r o w a v e g u i d e s ,O p t i c s L e l l e r s , V o l . 1 4 , N o . 1 1 , p . 5 9 3 - 5 9 5 , f 9 8 9 . Engheta, N., M.W. Kowarz, and D.L. Jaggatd: Effect of chirality on the Doppler shift and aberration of Iight waves, Journal of Applied Physics, Vol. 66, No. 6, p. 2274-2277, t989. Engheta, N., and P. Pelet: Orthogonality relations in chirowaveguide, IEEE llansactions on Microuaoe T h e o r g o n d T e c h n i q u e sV , o l . 3 8 , p . 1 6 3 1 - 1 6 3 4 ,1 9 9 0 . Engheta, N. and P.G. Zablocky: A step towards determining transient response of chiral rnaterials: Kramers-Kronig relations for chiral parameters, Eleclrcnics Lellers, Vol. 26, No. 25, p. 2132-2133, 1990. Engheta, N., and P. Pelet: Reduction of surface waves in chirostrip antennas, Eleclrcnics Letlers, Yol. 27, No. 1, p. 5-7, January 1991. Dngheta, N., and P. Pelet: Surface waves in chiral layers, Optics Letters, Vol. 16, No. 10, p. 723-725, May 1991. Engheta, N. and P.G. Zablocky: Etrect ofchirality on the transient signal wave ftont, Optics Lellers,Yol. 1 6 , N o . 2 4 , p . 1 9 2 4 - 1 9 2 61, 9 9 1 . Engheta, N. (editor): Jovnral of Electrcmognelic Waoes ond Applicotions, Special Issue on Wave Interaction with Chiral and Compler Media, Vol. 6, No. 5/6, p. 537-?98, f992. Engheta, N., D.L. Jaggard, and M.W. Kowarz: Electromagnetic waves in Faraday chiral media, I88E Tlvrsoclions on Anteanos ond Prcpogotion, Vol. 40, No. 4, p. 357-467, April 1992. Evans, M.W.: Chirality of field induced natural and magnetic optical activity, Physics Letlen, A,Yol. 1 4 6 , N o . 4 , p . 1 8 5 - 1 8 9 ,1 9 9 0 . Fedorov, F.I.: On the theory ofoptical activity in crystals, Speclrcscopg,Vol. 6, p. 49-53, lgbg. T2 Fedorov, F.I.: TheorE of gyrotrcpy, Minsk, 1976 (in Russian). Georgieva, E.: Jones and Mueller matrices for specular reflection from a chiral medium: determination of the basic chiral parameters using the elements of the Mueller matrix and experimental configurations t o m e a ' s u r et h e b a s i c c h i r a l p a r e m e t e r c , A p p l i e d ,o p t i c s , Y o l . 3 0 , N o . 3 4 , p . b O g l - 5 0 g b , 1 9 9 1 . Ginzburg, V.L.: Advances in crystal optics, and F.L Fedorov: Theory of the optical ectivity of crystals (Discussion), Athtances in Physics (USSR), Vol. 108, No. 4, 1972. Godlevskaya, A.N., V.A. Karpenko, and A.N. Serdyukov: Spherical electromagnetic waves in naturally gyrotropic media, oplics ond. speclroscopy (ussV), Vol. sg, No. 6, p. ?5g-?s9. December l9gb. Godlevskaya, A.N., and V.N. Kepshai: Scattering of electromagnetic weves on spherically symmetrical particles in e naturally gyrotropic medium, Oplics onil Spectroscopg(USSR), Vol. 68, No. 1, p. 69-22, January 1990. Graglia, R.D', P.L.E. Uslenghi, and R.E. Zich: Reflection and transmission for planar structures of bianisotropic media, Eleclmmagnelics, Vol. ll, p. lg3-208, lgg1. Graglia, R.D., P.L.E. Uslenghi, and C.L. Yu: Electromagnetic oblique scattering by a cylinder coated with chiral layers and anisotropic jumpimmittance sheets, Journol of Electrcmagnelic Wotsesand. Applicalions, V o l . 6 , N o . 5 / 6 , p . 6 9 5 - 7 2 0 ,1 9 9 2 . Guire, T., V.V. Varadan, and V.K. Varadan: Influence of chirality on the reflection of EM waves by planar dielectric slabs, IEEE Tronsactions on Eleclromagnelic Compatibilily, Vol. 32, No. 4, p. 300-30i, 1990. Gvozdev' V.V., and A.N. Serdyukov: Gteen's function and the field of moving charges in a gyrotropic medium, optics ond spectroscopy (ussR), vol. 42, No. 3, p. 301-304, september l9?9. Gvozdev, V.V., V.A. Penyaz, and A.N. Serdyukov: Scattering of electromagnetic waves in gyrotropic media, Oplics and Spectrcscopy (USSR), Vol. 49, No. 6, p. 639-640, December lgg0. Gvozdev, V.V', and A.N. Serdyukov: Radiation of electromagnetic waves in a dispersive gyrotropic medium, Opiics and Spectroscopy (USSY), Vol. 50, No. 2, p. 1gZ-190, February 1981. Hanfling' J.D.' G. Jerinic, and L.R. Lewis: Twist reflector design using Dtype and H-type modes, 7EEE h w n s o c l i o n s o n A n t e n n o s a n d P r o p o g o t i o n , V o l . 2 9 , N o . 4 , p . 6 2 2 - 6 2 g ,J u l y - l 9 g l . He, S.: A time-harmonic Gteen's function technique and wave propagation in a stratified nonreciprocal chiral slab with multiple discontinuities, Journol of Molhemoticol Phgsics, Vol. 33, No. 12, p. f-a, December 1992. Hegstrom, R.A. and D.K. Kondepundi: The handedness of the universe, Scientific American, January 1 9 9 0 ,p . 1 0 8 - r 1 5 . Hollinger, R., V.V. Varadan, and V.K. Varedan: Eigenmodes in a circular waveguide containing an isotropic chiral material, Rod,io science, vol. 26, No. 5, p. l33b-1344, september-october 1991. Hollinger, R.D., V.V. Vatadan, Ghodkaonkar, D.K., and V.K. Varadan: Experimental characterization of isotropic chiral composites in circular waveguides, Rotlio Science,Yol. 27, No. 2, p. 161-16g, March-April 19 9 2 . Iloppe, D.J., Y. Rahmat-Samii: Gaussian beam reflection at a dielectric-chiral interface, Journal of Electrvmognetic Wooes and Applications, Vol. 6, No. 5/6, p. 603-624, 1992. Jaggerd, D.L.' A.R. Michelson, and C.H. 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Urry, D.W., and J. Krivavic: Diferential scatter of left and right circularly polarized light by optically active patticulate systems, Prcceedings ol the Nalional Academy of Sciences (USA), Vol. 65, No. 4, p. 845-852,1970. Varadan,V.K.,A.Lalhtatia,endV.V.Varadau: Acommentonthesolutionof theequationVxd=d, J o r n t o l o l P h g s i c s , 4 , V o l . 2 0 , p . 2 6 4 9 - 2 6 5 0 ,1 9 8 7 . Varadan, V.K., V.V. Varadan, and A. Lathtakia: On the possibility of designing anti-reflection coeting using chital composites, Jounrcl ol Wooe-Moteiol Intercction, Vol. 2, p. 71, 1987. Varadan, V.K., V.V. Varedan, and A. Lalhtalia: Propagation in parallel-plate waveguide wholly filled 1B with a chiral medium, Journol of Waae-Malerial Inleraction, Vol. 3, No.3, p. 267-272, 1988. Varadan, V'V., Y. Ma, and V.K. Varadan: Dfects of chiral microstructure on em propagation in discrete random medit, Rad,io Science, VoL 24, No. 6, p. 785-792, November-December l9gg. Varadan, V.V., R. Ro, A.H. Sihvola, and V.K. Varadan: Electromagnetic properties of chiral composite materials using Penn State free-space measurement data, Proc. Progrcss in Elechomagnelic Research S y m p o s i u m ,P I E R S ' 9 1 , B o s t o n , J u l y 1 - 5 , 1 9 g 1 , p . 3 3 4 . Varadan, V.V.' A. Lakhtakia, and V.K. Varadan: Microscopic circular polarizabilities (rotabilities) and the macroscopic properties of chiral media, .Rodio Science, Vol. 26, No. 2, p. 511-516, March-April 1ggl. Viitanen, A.J., I.V. Lindell, A.H. Sihvola, ond S.A. Ttetyakov: Eigensolutions for the reflection problem involving the interface of two chiral halfspaces, Jounral of the Optical Society of America A, Vol. 7, No. { , p . 6 8 3 - 6 9 2 ,A p r i l 1 9 9 0 . Viitanen A.J., I.V. Lindell, and A.H. Sihvola: Polarization correction of Luneburg lens with chiral medium, Micrcuaoe anil opticol rechnology Lefiers, Vol. 3, No. 2, p. 62-66, February lgg0. Viitanen A.J.: Polarization correction of Gutman lens with chiral mediun, Mictwuooe and.Oplicol Technology Lellers, Vol. 3, No. 4, p. 136-140, April 1990 Viitanen A.J., LV. Lindell, and A.fl. Sihvola: Generalized WKB approximation for stratified isotropic chiral media with obliquely incident plane wave, Journal of Eleclrcmognelic Wares ond Applications, V o l . 5 , N o . 1 0 , p . 1 1 0 5 - 1 1 2 11, 9 9 1 . Viitanen A.J.: Generalized WKB approximation for stratified bi-isotropic media, Jozrzal of Electromagnelic Waaes ond Applicoliozs, Vol. 6, No. 1, p. ?1-84, 1992. Viitanen, A.J. and I.V. Lindell: Perturbation theory for a corrugated waveguide with a bi-isotropic rod. M i c . w a o e a n d O p l i c a l T e c h n o l o g gL e t l e n , V o l . 5 , N o . 1 4 , p . 7 2 g - 7 3 2 , D e c e m b e r 1 g 9 2 . Weiglhofer, W'S.: A simple and straightforward derivation of the dyadic Green's function of an isottopic chiral medium, Archio fir Elekttonik und iberlmgungstechnik, Vol. 43, No. l, p. bl-52, 19g9. WeiglhoGr, W.S.: Electtomagnetic field representation in inhomogeneous isotropic chiral media, t r c m o g n e l i c s ,V o l . 1 0 , p . 2 7 1 - 2 ? 8 , 1 9 9 0 . .Olec- Zouhdi, S., A. Fourrier-Lamet, and F. Mariotte: On the relationships between constitutive parameters ofchiral materials and dimensions ofchiral objects (helices), Journol of Phgsics III, Fronce, Vol. 2, p. 337-342, March 1992. l9 ELECTROMAGNETICS IN NOVEL ISOTROPIC MEDIA I V Lindelll ABSTRACT Basic relations of electromagnetic fields in bi-isotropic media are briefly discussed. Such media are more general than the ordinary isotropic dielectric and magnetic media because they can couple electric and magnetic polarizations. Bi-isotropic media have interesting possible applications and the main problem today lies in the fabrication, which has not yet reached an industrial level. However, before starting making suc.hmedia, their usefulness must be shown theoreticallv. INTRODUCTION Isotropic chiral media have raised interest in the last decade due to their extra medium parameter which gives added freedom in designing microwave and millimeterwave devices. In fact, promising applications in antennas (polarization rotating lenses,compactly packed microstrip antennas),microwave devices(low-lossphase shifters) and radar engineering(reflectionlesssurfaces)have been suggested,all based on isotropic chiral media. New applications have induced interest in electromagnetictheory for such media [1,2]. Actually, chiral media form a subset of the most general isotropic media, the bi-isotropic (BI) media, which again form a subset of the most general linear media, the bianisotroprc media. Electromagnetic wave propagation in and reflection from such media is consideredin this paper. The basic phenomena, rotation of polarization, in propagation due to chirality and in reflection due to nonreciprocity, of the BI medium, are discussed.Transmission-line analogiesare given to treat layered structures of bi-isotropic media. As an example it is shown that a twist polarizer can be simply constructed with just a layer of BI material on a conducting plate. THE BI MEDIUM The medium is seenby the electromagneticfields through the constitutive equations, which for time-harmonic fields (ept dependence)have the general form involving four medium parameters [3, 4] D=eE*{H, (1) B=pH+(E, (2) or in terms of other parameters[6, 7, 5], where n is the chirality parameterand 1, the Tellegenparameter: €: (x - jn)Jp"e", ( = (X+ jn)Jtr"e". (3) The relative chiral and Tellegen parameters lHelsinki University ofTechnolog;r, Electromagnetics Laboratory, Otalaari 5A, Espoo 02150, Finland 2L Kr: ,t -l X' = sind n x) with ": Trt, : yE,e, (4) tl}t'o "o Y will also be applied to simplify the notation. The present form of the constitutive equations is not the only possibleone and severalother notations are in use in the literature. Different forms of the constitutive relations for BI media are discussedin [5]. It is quite easily shown that, for losslessmedia, the parameters x and 1 together with e and - (p have real values, which with other symbols can be written as { [3]. Also, it can be parameter the Tellegen if and only if is reciprocal medium 1 vanishes shown that the BI parameter. Both nonreciprocity called as the also be parameter can [10]. Thus, the Tellegen physical in meaning a simple parameter have rc and the Tellegen the chirality parameter t shortly. propertiesr be discussed to terms of plane wave A medium with nonzero chirality parameter ,r requires microscopic constituents without mirror symmetry, e.g., small -glallic heliceswith the same handedness.Actually, first electromagnetic experimentson a man-made chiral medium were done in the 1910'swith copper helices randomly embedded in cotton [8]. The Tellegen parameter X can be theoretically realized by a medium whose microscopic constituents are permanent electric and magnetic dipoles tied together to form similar pairs [9]. It is not known whether this kind of media have yet been actually fabricated. FIELDS IN BI MEDIUM Let us consider time-harmonic electric and magnetic current sourcesJ, J- giving rise to an electromagneticfield E, H in a homogeneousBI medium. The Maxwell equations r z - l -l s \l : & { X'' : 1 " \ "'\"/ \/e\ - l\=rl l - X , + r ^ , 1/ \l n; /- = \ -rrr /o -1 \/ J \ o i \l-i (, ,o, , , can be written in uncoupled form for a homogeneousmedium by writing the electric and magnetic fields in terms of uorse felds, also called self-duol electric felds 14, 6] E+, Edefined by p* : -l( cos u "-iou - jrt[), e- : -1( ' eou+ irirr.1, cos 1, (6) where 4 = lfUle.In fact, (5) can be written as the uncoupledequation pair v x E - + , b - E -: i q J -, YxE*-h*E*:-jqJ+, (7) with r) = fr(cosrl * r'), k* = k'6F 1i (8) if the sourcesJ, J- are split into two parts J1 and J- as follows: r* : =l ^(e*j'J+ lr-). zcosu (e) Jq The magnetic field can also be split into two parts, H = H+ * H-, which have a simple relation to the electric field: H+ = *1E+, 22 \+ = \erio, (10) and, similarly, the magnetic source has the decomposition J-* : J-1+iar + r+jrJ-). z cosl) (11) \\'ith these definitions, the Maxwell equations (7) can ia fact be written in the simple isotrooicform -J-+r V x E1 : -jup.alla VxHl-joe1E1fJ1. (1 2 ) (13) tt+t' fields This means, that if the sourcesJ, J* are split into two parts, the Ja gives rise to just like in a simple isotropic medium with the efective medium parameters p+: e + : e d o ( c o s r19r , ) , I l e - i o ( c o s r*g r , ) , (14) and the minus part to minus fields in another isotropic medium with - r,). ,t- : y,eio(cosd ,"-io("os t9 - r,), ,- : (15) This idea simplifies the analysis considerably,since at any stage we may find the efrect of a BI medium by a cumulative effect of two diferent isotropic media' PLANE \MAVE IN BI MEDIUM Plane wave propagation in a BI medium was first analyzed already in 1956 [12]. Let us consider a plane wave propagating in the positive z axis direction in a BI medium. Let the electric field at the plane z = 0 be written as E(0) = E+ * E-. Each of the two wave fields E1 see their own isotropic media and propagate with the propagation factors, whence the total field is E(z) = Eae-ik+' +E-e-ih-", kt: f , ( c o s r l* r c ' ) . uJiF+: (16) (1 7 ) The polarizations of the wave fields are obtained ftom (7), which outside the sourcesgives - jw, x E*(0) + ,t+E*(0): 0. (1 8 ) It is easy to seethat the field vectors are transversal to u" and circularly polarized, because they satisfy E+ 'E+ - 0 and, moreover, the plus wave has the right-hand and, the minus wave, the left-hand polarization. Thus, we may write 1 E(z) : !r-ih'co"o(trtol - JU, X E(o;]r-;*t' + tE(0)* ju, x E(0)]/-t") "-ik'"-0lcos(r[z)71 Ir=I-u,u' - sin(r,tz)7] .E(0), J:urxI. ( le) (20) The dyadic in square brackets is a rotation dyadic which turns the vector E(0) by an angle -n,kz - -xkoz in the right-hand direction when looking in the direction of propagation, u,. Thus, the chirality parameter r has the simple physical meaning: it gives the rate of polarization rotation of a propagating linearly polarized plane wave, relative to the rate of 23 The phase changeof the wave in air: at a distance of )" the rotation angle equals 6:2trn. function exponential with a dyadic rotation dyadic can be written in the compact form ,= cos(nk"z)I 1- sin(r,t"-)7 = s-nkozJ (21) The polarization rotation in the BI medium is seen to be due to the chirality parameter, becausethe Tellegen parameter only affects the phase change of the wave. The effect is similar to the Faraday rotation in magnetoplasmaor ferrite except that it is the same in all directions of the wave becausethe BI medium is isotropic. This effect has many possible applications in microwave engineering. For example, a polarization correction for a lens antenna fed by a dipole, by introducing suitably distributed chirality in the lens material, has been suggested[11]. The magnetic field of the plane wave can be written as H ( z :) H + ( ,+) : f - - ( z ) :! n * 1 " 1 - !q-" - f " l \+ j n ' h z - '."o+1"121.8(r). (tefol - ju" x E(0)]e: 1 [ E ( 0 ) + j u , x E ( 0 ) ] e i K " k' ' z ) t \'! rl tztzl This can be interpreted so that the magnetic field of the plane wave is rotated by an angle 3 +T 12 with respectto the electric field. Thus, the Tellegenparameter X : n.sin rl is directly related to the excessangle 19over the right angle of the electric and magnetic field. 1L1- " - i k ' " o " o NORMAL REFLECTION tr'ROM AN INTERFACE Let us considerthe plane wave incident from air to an interface of a BI medium at z : 0. In normal incidence the problem is easily solved by writing the incident field as a sum of two circularly polarized fields, which do not couple but changeplaces in the reflection. In fact, becausethe field vector must be rotating in the same direction before ans after reflection, the handednessis changed in reflection, whence the reflected wave seesanother isotropic medium than the incident wave. L e t t h e i n c i d e n t w a v e a r r i v e f r o m a i r z 1 0 t o t h e i n t e r f a c ea t z : 0 z > 0. Writing the incident field at the interface as E':Ei*El, of a BI mediumin (23) the reflected field is E ' ( 0 )= . R + E + l R - E ' -: E ' E ' , (24) ft:R+u+u-*rt-u-u*, ( 2 5) where the circularly polarized unit vectors are ,r*=;l{rr"-ruy), .,-:;l{,r"+ruy). ( 2 6) Inserting n J L*+ = l- .x - r l " ?t*1o' 24 (27) the reflection dyadic (25) can be written as [6] F = |ta* + ft-)7,- t;W* - R-)i - R"6i, ( 28) where .R denotes the total reflection coefficient and {, the angle of rotation of the reflected polarization, R_ T2 - 2T\" cosri I ql T 2l 2 q \ o c o s 8 1 r 7 l ' t a n g -- + + s i n r 9 : (2e) 2x (30) e,-Fr \'-n; It is seen that the chirality parameter r does not affect the reflection at all. On the other hand, the Tellegen parameter x causesrotation of polarization in reflection. flowever, +g0" rotation is possible only for €, : p.. The reflection rotation is another quantity giving physical meaning to the Tellegen parameter a. The rotation of the reflectedfield is a demonstration of nonreciprocity of the BI medium with nonzero Tellegen parameter. In fact, a field incident with the polarization of the reflected field does not reflect with the polarization of the incident field but is rotated by another angle /. This efect also exists for BI slabs and it may find important applications in the future when media with nonzero Tellegenparameter can be reliably fabricated. LAYERED MEDIA, NORMAL INCIDENCE The previous concepts can be applied to a piecewisehomogeneousBI med-ium where the interfaces are planes perpendicular to the z axis. If a plane wave is incident in u, direction to the layered structure, in each homogeneoussection the field can be expressed.in terms of four waves: one plus and one minus wave in both directions. The plus wavesin *u, direction are coupled only to minus wavesin -u, direction and vice versa. So the problem can be split into two scalar problems which can be handled through transmission-linetheory except tlat the properties of the transmissionline are diferent for wavestraveling in opposite directions. Thus, we are motivated to study a more general transmission theory [lB]. GENERALTZED SCALAR TRANSMIS SION-LINE THEORY The generalizedtransmission-lineequations are written in matrix form as W)':-,,("2,u ), "l,u)(?,,;i (31) where prime denotes differentiation with respect to z. L is the distributed inductance and C the capacitanceon the line. a and 6 are two new parameters of the transmission line and they may have complex values, although for losslesslines they are real. To emphasizethe connection to the field theory, we can write o = *.Jid, g = y,t/Td : sinoy/LC. (32) It can be easily shown that the propagation factors for waves propagating in the opposite directions are analogousto those of the previous sectionsif the plus wave is p.oprgrliog io the positive z direction 25 - 9t :IJLC:b2lua= B ( c o s d *r c , ) , (33) B:uJLC. are impedances characteristic The corresponding nr B+ a w(a + ib) uC uL - 2"1i8, B+au(a-jb) I - : r tr o ,cl : T (34) The most general voltage function is, then, of the form U(z) : g+ z [J- dP-', + "-iB+ (35) and the correspondingcurrent function, I(z) = 1+ z - y-g'"iBz I- dp-' - y+g+ + "-i9+ "-iB+ = yl(J+ e-i(B+,-d)- g"i@-,-o)1. z (36) Reflection and transmission at a junction Let us consider a junction of two transmission lines 1 (, < 0) and 2 (z > 0) and a voltage wave incident to the junction in line 1, Ur+. There arisesa reflected wave and a transmitted wave with the reflection coefrcient -R and transmission coefficient? defined by Ul : TU{ U, : RtJ{, (37) From continuity of voltage and current at the junction we can solve for the two coefrcients: Zl(Zl - Z{) n Yr* -Yr* ^:ffi:-iffi1fi=fr Z{ - Z{ *fi"'jo" T ' ==Y , + Y + _ Z l ( Z { + Z t ) _ 2 Z l " o ' 3 r " i 0 , . V7*4,:27127*27: z; * ^ ( 3 8) (3e) The last expressionsare only valid for a losslessline I with Z{ = /rs+i0'. The coefrcients defined for voltage amplitudes appear simpler in terms of admittances. Definitions in terms of current amplitudes are not the same because of. Z+ I Z- and, they appear simpler in terms of impedances. Similar expressionsare valid for the reflection from a load admittance Ys,when the admittance Yr+ is replaced by Y6 Z,(Zt - Z{) ZiQt+ Zr) Y r *- Y " '^" Y, +Y1 (40) Unlike for ordinary transmission lines, the magnitude of the reflection coefrcient is not necessarilyunity for the casewhen all the power is reflected. For example, for open circuit at z = 0, we have Yr. = 0 and y.+ R-=$=e2io' r1 instead of .R = 1. For short circuit Yr = * (41) we have Rr": as for the ordinary line. 26 -I (42) Input impedance The reflection coefrcient at a point z ( 0 in line 1 can be written as R(z):ffi: : R(0)etze,"o"o.(43) R(o)ei@++B-), W#: Aga.in,it is noteworthy that the parameter o, or r,, does not affect the reflection coefrcient. The admittance at the point z < 0 of a line loaded by an admittance Y1,is -Y-U-(z) -Y- R(z) +U+(z) _ vtit\o) . r , \ :_ I ( " ) _ Y__uIrTu_A_ : Y+ ue): :t, I + R(r) ,,Y7cos(Bd,cosd + rl) * jY sin(pd cosr9) (44) The correspondencewith the expressionof the ordinary line is seen immediately. In fact, setting d : 0, the well-known expression r, ri^: cosBd * jY sinBd ,,Y1 r Y"""pd+ jY"t]"N (45) is obtained. Impedance matching The quarter-wavelengthmatching sectionof the ordinary transmissionline can be generalized for the present transmissionline. Requiring that the imaginary part of the input admittance (44) vanishes,gives us the following relation between the parameterc Bd,,$ and,YelY: sin(Bd cos0)[Y] cos(Bdcost9 + 0) - Y'cos(Bd cos19- d)l = O. (46) Excluding the simple solutions sin(Bd cosd) : 0, for which we have Yn : Yr, there is another set of solutions satisfying =ffi tan(Bdcosrg)tanr9 (47) Apply*g this condition in (44) gives us the simple relation -Y' u t n. - (48) yLt which is the same as for the ordinary quarter-wavelenthline. Thus, if we wish to match the load admittance Y7 to an admittance Yo, the line admittance must be chosenas y:\ffi,. (4e) Flom (47) it can be seenthat, fot 3 I 0, the matching length of is changedfrom the ordinary vralueof quarter wavelength and shorter matching sectionsare in fact possible. I n t h e u l t i m a t e c a s e ,c h o o s i n g0 = r 1 2 f o t Y 1 ) Y a n d 0 : - r 1 2 I o t Y 7 1 Y , ( 4 7 ) b e c o m e s po=l##,1, or o= +;lTITFl _ ^2lY? -Y2l (50) This gives always d values smaller than )/4. Actually, the length depends on the mismatch of the two impedances: for small mismatch (hlY" = 1) the required iine length is small, 27 whereasfor the most completemismatch (YrlY = 0 or YtlY = o), the length is )f 2r x )/6. This means more broadbanded matching than with a quarter-wavelengthsection of a conventional transmission line. GENERAL PLANE \^/A\/ES IN LAYERED BI MEDIA Finally, we consider general plane-wavepropagation in a piecewisehomogeneouslayered BI medium with plane-parallelinterfaces [14]. In this case,the plus and minus waves couple to one another and the problem cannot be handled in terms of two separatescalar transmission lines as for normal incidence. Also, in the simple isotropic case (x : 0, X : 0) with obliquely incident plane waves, the TE and TM polarizations do not couple to each other, which again leads to two scalar transmission lines. In the general BI problem the TE and TM polarizations have no special importance. Let us assumethat the plane waves are propagating normal to the c axis, which imposes no restriction to generality. For a single plane wave excitation, wavesin all layers propagate with the same velocity in the g direction, which implies that all wave vectors have the same component &r. It turns out that in each layer there are four plane wave components with the same &, component: two plus waves and two minus waves [15]: '* E1 e-jf*''-1E(r):fr* s-ji1''* fr[- ,-;i- ', "-;i,-;[-'' H(r):fr* s-ji+'* fr- .-;i-''* fi* "-ji*'1 fi- (orl (52) The vectors denoted by 9 correspondto r{'avespropagating in the positive z direction ani, those denoted by E, in the negative z direction. It is assumedthat the propagation factors Ba and p- defined by k+: u,9+ I ur,ty, kr: g_:1fk_-nu, -ur0+ * tvky, (53) k+:k"( (54) n2-y2tn). have a positive real part. Becauseof the coupling between scalar transmission lines, the general plane-waveproblem leads to a concept which can be labeled as vector transmission line. VECTOR TRANSMISSION-LINE THEORY In the vector transmission-line (VTL) theory, the transversal field components are represented through the tvector voltage' e and 'vector current'j defined by e:1r.E j:-u"xH=-J'H, (00J The vector voltage in a homogeneousregion can be written in terms of those corresponding to the four eigenwavesand the result presented in the compact form with two dyadic propagation factors, one for each direction of propagation, e ( z )= s - i i ' . - ( o )+ r ' F ' . ; ( o ) , + R_R =)++l++l 0: 9+ a*a* *6- B-8-, 28 (56) e + t ^ F e l a+a+ +p- a-a_ (0/J The basis vectors C*, E* are the transversal projections of the circular polarizations of the electric wave fields propagating in the respective *u, directions: i+: E+: u" I jcatr, u" T rc+uy, c + : c o s0 + : / x . l k + , (58) J : u,' d1 x d-: j(c1+ c-). (59) and their reciprocalvectorsare +t * 1 d*: +ju,x ia, The basis {d*,d-} tst i*: ,1 +ju,x i*= and the reciprocalburis {d'1,d'-} satisfy the orthogonality relations (60) The two propagationdyadics and simil6,llyfor the other basisvectors{f,*, f -}, {;;,;'-},. €+ * if 9+ and &1 are real (losslesscase). are not independent, in fact, they are related by 0:9 For a lossy medium, the relation is a bit more complicated [15]. The dyadic characteristic admittance for the transmitted wave can be easily identified from expressionsof the transmitted vector currents i e)=i .i ("), (61) in the form -u", i (i*;'* - ;-;'-), \-l \?* F t F F t \ q a-a_ I / a*a, (62) i: I'=u,^Jlq-l \?+ The relationbetweenthe two dyadicadmittancescan be written for losslessmediasimply € = -1", I / F where denotesthe transposeoperation. as Y:Y For a vector transmission line z ( 0 terminated al z :0 defined through the relation j(0) :ip with a dyadic admittance 7r, .e(0), (63) a reflectiondyadici 1r; ."o be definedfor wavesreflectinginto -u, direction: E(,):i (z).;e) E1r; ".o (64) be expressedin terms of admittance dyadics as follows (65) for the input admitt"o.. fr," (z) is obtainedftom the reflectiondyafic Finally,an expression expression in the form i + -7 $ J - y;^ (") = ly .s-ta' . V - yt)-'-.2+:t.:+:+ e .: e $ y .dp' . (y + yL)-'). . l e - t 0 '. 1 y _ y t ) - , + d p ' . ( y + r r ) - t ] - t . (66) Other forms can be found in [15]. After some algebra, the expression (66) can be seen to reduce to the well-known isotropic formula for normal incidence when 7; is a multiple of the unit dyadic 7,. 29 APPLICATIONS OF VTL THEORY there determinant of the reflection dyadic is zero' If we require that the two-dimensional one that of the plane wave' -since this means arises an equation for the angle of incidence zero' is polarizations *hith do not changein reflection) of the eigenpolarizations(transverse an explicit expression Brewster angle. After considerablealgebra' the angle can be ""X.dt;: in the form i.t ti""S."*ster angle 0B can be obtained (67) tan'208:*ffi' with R_ (68) | - Qln-)'1 | - (tln*)2 U+- (n*-,t")(n - \") (6e) 6TiJC+iJ whence R is a real quantity' In this case' : \!, For a losslessBI medium we have \+ isotropic interface we have, by setting tn.'.iropl" fo, t, solutio;r angle (67) has real the well-knownsolutions c+ :;- = JW, - L)lp,q and R = ('t T)lQt * q")' (?o t:n0",=l#. =mr tandel it turns out that two real Brewster angles There is a new phenomenon, however, because may exist for certain media [16]' Asanotherexample,letusapplytheVTLtheorytotheproblemofaBlslabbackedby aconductingplane'f,'ft'"tppfi"ationsandtestsofthetheorycanbefoundin[15]'A for the correspondsto ?t'= *'whence the expression perfectly conductingplane at z:0 reducesto iopot ui-ittance (66), for normal incidence' (Jr,l rl)7,+ sinr97l, i ,^ Q) = l1i .o. 0 cot(kzcos dyadic has the form rralid for z < 0. The reflection corresponding R*i i: (17,*7,,)-''r!7,-7..): R"'7,+ (72) tto 4o defined by the expressions with the co and cross-polarizedreflection coefficients d) 1 cos2r9+ (rt' 4l) sin2(/cdcos @dcosrl)12-4lsin Rn= -@cosrl)]2-4lsin /cdcosd) 2qt7os|mt9sin2(lcd cos 19) r9sinz( lcdcosrl ) For losslesscase,these coefficientssatisfy In-lt + l8-lt , (73) (74 = 1. slab of BI medium, the co-polarizedreflection If we wish to design a twist reflector with the condition between the parameters lcd' r9 is required to vanish. Thi, h"ppeos if the following and 4 is valid [17]: 30 si n(&d coso1 = J:22!--- . \/\; - \" ( 7 5) This has real solutions for losslessBI media only for q l q " < l s i n r 9: l 1 1 ' 1 , (76) whidr requires nonzero Tellegen parameter 1. The twist reflector rotates the reflected field by 90" and gives a phase shift in reflection defined bv (77) 1b: cos-r(T/4" sin r9). , "i{ This effect can be obtained even for small values of 1if Ilrl"i" small enough to satisfy the above condition, but, a broad-bandedoperation is obtained fot r7fq": 0.8 when 1, is chosen slightly larger than TlTo, as is seenin the figure. Rn = o'91R.o 0.8 0.7 0.6 0.5 0.4 U.J 0.2 0.1 0 0 reflectioncocfficicntfor a plancwavc incidcntto a layerof bi-isotropic Co-polarized medium with a conductorbacking,as a function of normalizedthickness&d. The n o r m a l i z e idm p e d a n c he a st h e v a l u e q fq . : 0 . 8 a n d t h e n o r m a l i z eTd e l l e g e np a r a m e t c r v a r i e sb e t w e e nX , : 0 . 7 . . . 1 . 0 . l t i s s e e nt h a t t h e c o - p o l a r i z erde f l e c t i o ni s s m a l l for a wide band when 1, has a valueslightlylargerthan qf q". References [1] A. Lakhtakia, V.K. Varadan, V.V. Varadar, Time-Harmonic Electromognetic Fields in Chircl Mediq Berlin: Springer, 1989. [2] S. Bassiri, "Electromagnetic wavesin chiral media", in RecentAdt:ancesin Electromagnetic Theory,eds. H.N. Kritikos and D.L. Jaggard,New York: Springer,1990,pp.1-30. [3] J.A. Kong, Electromagnetic Woae Theory. New York: Wiley, 1986. 31 ,,Radiation and scattering in homogeneousgeneral bi.isotropic reSions''' [4] J.C. Monzon, pp'227-235' Febtuary 1990' I E E E Trans. Antennas Propagat', vol'38, no'2' constitutive relations", Microwaue and opt' t5l A.II. sihvola, I.v. Lindell, "Bi-isotropic Tech. Lett.,vol.4,no.8, pp'295-297,July 1991' general bi-isotropic (nonViitanen, "Duality transformations for the [6] I.V. Lindell, A.J. reciprocalchiral)med.ium,,.IEEETrans.AntennasPropagat.,toappear,vol'40,no'1 JanuarY1992. [ 7 ] I . v . L i n d e l l , A . H . S i h v o l a , A . J . V i i t a n e n , ' ' P l a n e - w aTech. v e r eLett'' f l e c t vol'5, i o n f r ono'2, m a bpp'79-81' i-isotropic Opt. (nonreciprocal ctrirJ) interface". Microuorse ond FebruarY 1992. [ S ] X . f , i n a m " o , t U b " ' e i n e d u r c h e i n i s o t r o p e s S y s t e m v o Wellent', n s p i r a l f i Ann. irmige n R e svol'63, onatore Phys', erzeugte Rot.tioorpoirrisation der elektromagnetischen n o . 4 ,p P . 6 2 1 - 6 4 41,9 2 0 ' [9]B.D.E.Tellegen,,,TheGyrator'anewelectricnetworkelement'',PhilipsRes.Rep v o l . 3 ,p P ' 8 1 - 1 0 11, 9 4 8 ' media"' Microuate and Opt' Tech' Lett'' l10l I.V. Lindell, "On the reciprocity of bi-isotropic to appeartvol' 5, June 1992' ['--' 1 1 ] I ' v ' L i n d e l l , A . H . S i h v o l a , A . J . V i i t a n e n , S . A ' T r e t y a k ocorrection v , ' ' G e o min e t rinhomogeneous icalopticsininh *og"o"ous chiral media with application to polarization pp.533-548,1990' lenJantenn.sr,,J. Electro.WauesAppI.,vol.4, no.6, medium"' Quart' Jour' Mech' Appl' I12l t.G' Chambers, "Propagation in a gyrational M o t h . , v o l . 9 ,n o . 3 ,P P . 3 6 0 - 3 7 01,9 5 6 ' [13]I.V.Lindell,M.E.Valtonen,A'H'sihvola,"Theoryofnonreciprocalandnonsymm rictransmissionlines,,HelsinkiUniu.Tech.Electromagn.Lob.Reptll7,May1 Submitted lor IEEE Trans' Micro' Theory Tech' isotropic and Tretyakov, I.V. Lindell, "vector circuit theory for [14] M.I. oksanen, S.A. 1990' pp'613-643' chiral slabs", J. Electromag'WauesAppI',vol'4' no'7' ''Vector transmission.lineand circuit theory Tretyakov, M.I. oksanen, [15] I'v. Lindell, S.A. AppI', to appear' for bi-isotropic layered structures", J. Electro' woues of isotroprcsihvola, "Explicit expression for Brewster angles [16] LV. Lindell, A.E. pp'2163-2165'November1991' biisotropicinterface", Electron' Lett', vol'27,no'23' slab as twist Tretyakov, M.I. Oksanen, "conductor-backed Tellegen [17] LV. Lindell, s.A. 1992' anuary J 1282' pp'28 polarizet," Electron.LetI', vol'28,no'3, 32 Dictionarv between different definitions of bi-isotropic material parametres Ari Sihvola Helsinki University of Technology,Electromagnetic Laboratory Otakaari 5 A, 02150Espoo, Finland Due to the fact that there coexist different ways of expressingthe constitutive relations of bi-isotropic media, and furthermore, that the quantities used in these may carry the same name without obeying the same definition, it is essential to write explicitely the interconnectionsbetween these. The present report servesthis purposel. As a practical rule of thumb (often neededin the Workshop's discussions),which will be derivedin this report, among others,is the following: Ir you s E E s o M E B o D y p R E S E N T I N GR E S U L T s o F c I t I R A L M E D I A , , l . N o s t t o ( n e ) TALKs ABour c H I R A L I T v A D M T T T A N o E S( € " ) , A N D y o u wISH To KNow rHE Dr- M E N S I O N L E S SC I I I R A L I T Y V A L U E O F T H I S P I E C E O F M A T E R I A L , M U L T I P L E T H E A D M I T T A N C E F I G U R E B Y T H E F R E E S P A C EI M P E D A N C E , 1 O HAvE THE CHIRALITY PARAMETER r. terials where p = - 3 7 7 Q , N T T OY O U W I L L This is approximate, and exact only for ma- po, but the erperimental results so far show permeabilities not much diferent from ps. Should you desire more accurate transformation formulae, please keep on reading :-s The basic relations Most of the presentationsgivenin the presentBz-uotropics'93workshopspeakabout bi-isotropic media using the languageand terms of the following constitutive relarMuch of the material to follow is common to that in [1]. 33 tions: D=eE +(x- jn)J-p,oe& (1) B:pE+(x+jK)JpoeoE (2) The relations give the effect of the electric (E) and magnetic (,F) field strengths on the electric (D) and magnetic (B) flux densities.The effectscan be seento be isotropic (i.e. the direction of the fields does not matter), becausethe coefficients representing the linear relation between these are scalars. These parameters ate, in addition to the normally encounteredpermittivity e and permeability pr of the material, those that describethe magnetoelectriccoupling. The degreeof chirality is contained in rc, a dimensionless(Pasteur) parameter, and 1 is the (also dimensionless)Tellegenparameter measuringthe nonreciprocity of this generalbiisotropic material. €s and ps are the permittivity and permeability of the vacuum. For 1 - 0, the medium is (nonreciprocal) chiral, and it can also be termed Pasteur medium. The case when the chirality vanishes,r : 0, representsa nonreciprocal medium, that can be called Tellegenmedium, becausethe form the constitutive relations that Tellegenfirst proposed for a nonreciprocalmedium was of the form of (1), (2) with rc:0. It is worth noting that these relations implicitely assume sinusoidal time dependence (followed with the convention exp(ja.,t) in this paper), meaning that the parameters are dispersive. The time dependencecomesthrough the inverse Fourier transform, and in order to render real electromagneticfields (to representa physical quantity), the parametershave to be real functions of jo. On the other hand, the four material parametersof a losslessmedium haveto be real [2],leadingto the conclusion that e, ptryhave to be even functions of r.r, and rc an odd function. Hence, there is no chirality in electro- or magnetostatics. In the researchof chiral media, there are many different constitutive relations in use (see,for example [3]) due to the possibilitiesin connectingthe electric and magnetic quantities with another. In the following, the parameters in different sets of constitutive relations are related with each other, This will help translate electromagneticresults derivedin one system to the other system. The most common chirality representationswill be treated and their extensions to the nonreciprocal chiral regime, i.e., the chiral constitutive relations that are consideredwill be generalized for bi-isotropic media. The problem will be that in different systems,the same name has been given to parameters that are not absolutely the same, for example permittivity and permeability. Therefore bookkeepingis essentialwhich system's permittivity is considered as one speaks about permittivity. In the following, il relations are referred against 34 the constitutive relations (1), (2) and this permittivity is plain e and permeability plain p in the following analysis. The correspondingparameters in other systems are denoted by subindices. Post relations The Post [4] set of constitutive relations for chiral media, also derived phenomenologically by Jaggard, Mickelson, and Papas [5], is the following D:eerE-ie"B _t H: - (3) B-ie"E (4) Ppt where the subindicesin e and /.r,now refer to the system, and the chirality comes forth through the chirality admittance {". To completethe relations in order to cover generalbi-isotropic media, a fourth scalarparameter describingthe nonreciprocity is needed. In harmony with the chirality admittance (", a nonreciprocity susceptance ry'^is here suggested,which also has the dimension of amperes/volt. The relations, after the inclusion of nonreciprocity, look after that like D:err0+rlr^B-je,B _1 H-_B_rb^E_je"E (5) (6) Uot The connectionsbetweenthe parametersin (5), (6) and (1), (2) can be worked out and are the following Foeo, t €pt=(-::::(y'+x') p a Pps=P (7) (8) ' JP"" 9n= -X Lt (e) ' -Jlt'eo lc lc = lL (1 0 ) and, the other way €:€rr+ttrtb!'"+€l) 35 (i1) F: ( 1 2) Ppt X: trr'{^lJPoeo (1 3 ) n: p'r,LfuQseo (14) Condon-Tellegen relations The constitutive relations of chiral media that have receivedtheir label after Condon [6],look like the following, permitting an explicit time dependencein the fields: D:e"E-X"T (1 5 ) Ap B:p"E+X.fr (1 6 ) with the parameter 1" (now not a nonreciprocity parameter) measuring the material's magnitude of chirality (dimension sec2/meters). This is a reciprocal chiral material. On the other hand, a material that is not chiral but is nonreciprocal was suggested by Tellegen [7] to obey the following constitutive relations D=rrE*rE (1 7 ) B:pril*tE (18) where 7r, dimensionally sec/meters, measuresthe nonreciprocity of the material. These material relations can be combined for a set of bi-isotropic constitutive relations: D: e.,E *j.,8 - x.,* B : rr..E* -t",E + x.,# (19) (20) For time-harmonic field dependence,the connectionof these material parameters t o t h o s ei n ( l ) , ( 2 ) i s €ct=€ 36 ( 2 1) (22) Fcr = lt 7", : y.r: 4 Drude-Born-Fedorov (23) Y1/1t'seo (24) n1/ffif u relations The relations emphasizingthe nonlocal characterof a chiral medium in its interaction with the electromagneticfield, E) (25) B: po"*(E + Bv x E) (26) D = eo"*(E* 0Y x have been in much use by Lakhtakia, Varadan, and Varadan, and termed by them [8] after Drude, Born, and Fedorov. (An advantagein these relations is that these are not restricted to Fourier space,and the fact that from these, it can be directly seen that chirality vanishesfor electro- and magnetostatics.) Here the chirality parameter B has the dimension of length. One way of incorporating nonreciprocity in these relations would be through the Tellegenparameter: D:eo",(E+pVxE)+rE (27) B : p o " , ( E+ p v x E 1 +7 E (28) However, as often only time-harmonic field dependenciesare consideredin electromagnetic applications, it might be justified to tolerate complex quantities and the appearanceof the imaginary unit j in these relations (like happens in relations (1), (2) and (5), (6)). This suggestscompletingthe bi-isotropic DBF relations in the form D=eo",lE+(9+ja)vxE) ( 2e) B=po".LE+(p-jo)Vx//l ( 3 0) where now the nonreciprocity para-eter a has the same dimension of length as the chirality parameter p. 37 The conversionof the material parametersbetweenthe sets (1), (2) and (29), (30) is, for time-harmonicfields r po€o'l € o g r = e l l _ A ' l n 2 ' 1,- , TLE) L (31) f. , ) z'Poeol posp:tLt-{X"+x'l;) ( 3 2) o= ^ P: xJtt'oeolu rr 1r4 *'7r* n Jltseolu p€-A?'+K2)ttoeo ( 3 3) (34) and, inversely, €oop (35) f f i r-K;BF\a'+p') p: Itoar t-kf;",(a2+02) ulto"reo"raf X_ K: ,Foeo r-k2o"r@2+82) upo"r€o"*9lJW" t-kf;",(a2+92) (36) (37) (38) with k'or* : a2 P'o"reo", ( 3e) Discussion A generalbi-isotropic medium requiresfour scalarmaterial parametersin its characterization, In this presentation,insteadof connectingthe electromagneticquantities in a classicalway, through a matrix [9] /D\ \B/ (,1\/E\ =\p p)\H) (40) the effects (electric and magnetic polarization, chiralityand reciprocity)are separated in the constitutiverelations( i ) , ( 2 ) : (3)=( ,, * ,ilu',n 38 a- i4'/r';a ( t \ ) E) (41) For a lossy material, all these four parameters can be complex for time-harmonic excitation of the fields. In the other systemsof constitutive relations that have been briefly discussedin this communication, the parametershave been expressedas functions of the material parametersof (1), (2). It is worth noting that in all these transation formulas, always the permittivity, permeability, and nonreciprocity are even functions of chirality (given in one of the other systems). This means that these three parameters are equal for a material and its mirror image (which is a medium possessingr with a changein sign with respect to the original medium). Also rc is an odd function of a.ll chiralities of the other notations, which also agreeswith intuition. Not so intuitive is that also nonreciprocity behavesin a similar way, a fact that is reflected by the similar position of 1 compared to rc in the expressionsabove. In other words, also the permittivity, permeability, and chirality are even functions of nonreciprocity. And again in the translation formulae, nonreciprocity is itself always an odd function of the nonreciprocity parameter of the other notations. References A.H. Sihvola, and I.V. Lindell: Bi-isotropic constitutive relations, Micrcwaue and Optical TechnologyLetters, Vol.4, No. 8, p. 295-297,1991. J.A. Kong: Electromagnetic wate theory, Joh.n Wiley & Sons, New York, 1986. A, Lakhtakia, V.K. Varadan, and V.V. Varadan: Time-harmonic electromagnetic fiekls in chiml media, Lecture Notes in Physics, 335, Springer-Verlag, Berlin 1989. E.J. Post: Forrnol stntctutE of electrcmagnelics,North-Holland Publishing Company, Arruterdam, 1962. tDl D.L. Jaggard, A.R. Miclelson, rnd C.H. Papas: On electromagnetic waves in chiral media, Applied Physics, Vol. 18, p. 211-216, 1979. [6] E.U. Condon: Theories of optical rotatory porper, Reriews of Modern P/rysics, Vol. 9 , p . 4 3 2 - 4 5 7 ,1 9 3 7 . B.D.F. Tellegen:The gyrator, a new electricnetwork element, PhilipsResearchReporls,Vol. 3, No. 2, p. 81-101,1948. [8] A. takhtakia, V.K. Varadan, and V.V. Varadan: Dilute random distribution of small chiral spheres,Applied,Optics, Vol.29, No. 25, p. 3627-3632,I September 1990. [9] J.C. Monzon: R.adiation and scattering in homogeneous general biisotropic regions, IEEE thnsactions on Antennos and Prcpagatioa, Vol. 38, No. 2,p,227-235,L990. 39 THEORY OF GUIDED WAVE IN CHIRAL MEDIA : A STEP FOR MEASURING CHIRAL MATERIAL PARAMETERS Fr6ddric Mariotte CEA-CESTA ServiceSystdme BPNo2 33 I 14 l,,eBarp, France. The constitutiverelationsof isotropiclossychiral compositeconsistingof chiral objectsfor time-harmonicfields exp(-irot)havethe form D = sp + ii.B and H = i E . E + B / p . w h e r ee . = € o ( t ' + i e " ) ,F c = [ r o ( F ' + i g " ) a n dE . = E 6+ i l i representcomplex perminivity and permeability,and chirality admittance,which is of the medium.Thesematerialspossesstwo bulk a measureof the handedness eigenmodesof propagation,a right circularly polarized(RCP) and a left circularly polarized(LCP) plane rvavewith two differing complex wavenumbers.Recentll', the guided wave propagationin chiral media has been the subjectof intense research.Among thosestudieswe can mention the introductionby P. Peletand N. Engheta llf of chirowaveguideswhich consist of cylindrical wave-guiding structuresfilled with isotropiclosslesschiral materials. In this talk, we review all the resultsof our recent theoreticalstudy on parallel-platewaveguidepartially filled with isotropicchiral materials(loss or lossless)[24]. First, we presentan overviewof the theory of chirowaveguides. Secondly, we analysethe study of the canonical problem of reflection and transmissionof guidedmodesat an air-chiral interfaceand at a losslesschiral slab transverselylocatedin a parallel-platewaveguide.In thosetwo problems,the chiral materials were assumedto be lossless;now we theoreticallystudy the effect of lossy chiral materialson guidedmodesin suchwaveguidesand furthermorewe analyze,first, the reflectionand transmissionof guidedmodesat a lossychiral slab (case a) and secondlythe reflectionof a lossy chiral slab backedby a perfect conductor(caseb).The motivationbehindthis study is the potentialapplicationof this problem in the design of novel measurementtechniquesfor determining of lossychiral composites. materialcomplex parameters So we have studiedthe effect of chirality and then the influenceof lossy materialsin all theseproblems.The resultsare the following. For our analysison reflection and transmissionof guided electromagneticwaves at an achiral-chiral (lossless)interfacein a parallel-platewaveguide,it is found that in order to satisfy 4I theboundaryconditionsattheachiral.chiralinterface,thereflectedandtransmitted we first presentthe restrltsof our wavesneedto be hybrrd' For lossy materials' analysisonthedispersionrelations,Brillouindiagrams,cut_offfreqtrencies. the modes lt must be notedthat for propagationand attenuationcoefficientsof lossychirowaveguide,thedispersioncun'esapproachthelinelqorkaccordingto w e h a v e o b t a i n e dt h e r e f l e c t e da n d t h e c h i r a t p a r a m e t e rssc a n d U c ' S e c o n d l y ' transmittedmodes(onlycaseb)andhaveevaluatedtheeffectofchiralityandthe lossofthemedrumonpowerofreflectedandtransmittedwa\'es.Finallywe in material for the potentialapplications addressrulesto solvethe inverseproblem characterizations.Electromagneticshieldinganddesignofdevicesandcomponents studies' could be also potentialapplicationsof these MicrorvaveChiralityResearchat In this talk, we presentalsobriefly other CEA-CESTA:First,modellingofheterogeneouschiralmaterialsbythecalculation secondlythe design scatteringof a chiralelement(thin helix) and of electromagnetrc [55]' andfree spacemeasurements) of chiral shields(preparationof chiral samples References tll l2l t3l IEEE Trans' P. Peletand N. Engheta,'TheTheory of Chirowaveguides"' 1990' AntennasctndPropagarion,vol'38' pp 90-98' and transmissionof guided F. Mariotte and N' Engheta.''Reflection electromagnetlcwavesatanair.chiralinterfaceandatachiralslabina publication in IEEE Trans' parallel-plate waveguide", acceptedfor in 1993' Microwave Theorv and technique't'to aPpear material loss on guided F. Marrotte and N' Engheta"Effect of w a v e g u i d e " 'a c c e p t e df o r e l e c t r o m a g n e t im c o d e si n a p a r a l l e l - p l a t e and Applications'lo publicationin Journal of ElectromagneticWoves aPPearin 1993. l4l lrom a lossychiral slab (with or F. Mariotte and N. Engheta,'Reflection submittedto Radkl without metallicbacking)in a parallel-platewaveguide'', Science,1992. 151 16l f o r p u b l i c a t i o ni n R e v u e F . M a r i o t t e , " C h i r a l i t e6 t f u r t i v i t 6 " ' a c c e p t e d in 1993' Scienrifqueer Techniquede kt Dlfense' to appear "On the relationships S. Zoudhi' A. Fourrier L:mer and F' Mariotte' betweentheconstitutivesparametersofchira|materialsanddimensionsof chiralobjects(helix)',EuropeanJournalofPhvsicsIII'Vol.2'No.2,pp. 337-343,199242 Measuring electrical, magnetic, and chiral material parameters Arto Hujanen State Technical ResearchCentre, Telecommunications Laboratorv Otakaari 7 B,02LS0 Espoo, Finland 43 Problem - unknown plane slab - what arethe electricalmaterial parameters t,l-[,K Measuringtraditional"nonchiral. material - two complexparameters g,lt - measuringmethods: - resonatormethods -eorp - low lossymaterials - reflectionI transmission methods - transmissionline methods - free spacemethods ssion methods Reflection/Transmi (o > - measurement of the reflected and transmittedfield - measurements aredonewith well calibratednetworkanalyzer 46 Transmissionline method sampleinside the waveguide - preparattonof the sample is difticult - gapsbetweensampleand waveguidemakeresults inaccurate 47 Free spacemethods - purposeto measurereflectedand transmittedsignalsin free space - no preparationof smallsamPles - problem:diffractionfrom the edgesof the slab 48 - focusingantennas - no edgediffractions -calibrationwith TRl-method - time domaingatingto avoid multiblereflections /,o yorivii antenni Liukukisko fL LZ 50 Calculatingmaterialparameters trom measuredS-parameters P - measuredS11- and 521parameters t.. 2+ - e,s,s".' ull )1 1 2St, r - K+/61 .r. S ,, * S r , - f 1- (S,,+ Sr,)f i k - L(ln(7)+n2n) ' rL L -= \0. J. + _ ^ .I- +2.... ;e.... d (.r cr' F, l-f k 1+f ko l+f k 1-I- ko C 1 2 N 3 4 R1 2 O c t ----x- Rc ( 51 1 ) ---€- Ra(52 1) Kuva 2.1 tS98: H 4z I HM T- t .21-t1 FREQUE|{CY --{im( 51 1 ) - - - - : t - ! r n ( S 21 ) perusaineelle Esinerkki nitatuista paksuus (hiilen osuus 4{;, naytteen C 1 2 N 3 4 R1 2 O c t t 9 9 8 : ( GH: ) S-pa:aner-reisti l-.2m) . H 4 z t ,H H T = t . 2 H i ,\l .\: ,rl 'r'')".'l I l. (€, .88 ---+--.F R c( E P S ) R e( H Y ) -iF -<- f.i .24 t4.88 E-;rnr |nrln ls- r 8 .e B lrn(EPS) !rn( HY) Kuva 2.2 Mitatuista S-parar.retreista . rnalla lasketut suhteel]iset - ja permiabiliteettik;iyrdt 52 (kuva 2.1) EpsMy-ohjeI p e r m i t t i i v i s y-y- . s _ (6.) tp-l. Measuringthe chiral material - three complex parameterst,l,l and t< = more measurements ateneeded - polartzattonof the wave ts changedwhen the wave goes throught the chiral slab - electricalfield behindthe slab E, : \ E,(n,+ tan(-kodK)u, ) - lets measurethe polartzatton propertiesof the transmittedtield 53 - transmitterandreceiverantennas linearly pol artzed ,-a- - sr",- S, cos(u) \-, AR sin( t) - 7cos( t) v -- AR cos(t)+7sin(t) S, sin(u) , , - -s , , t - . s . , t( l + G : ; + i r\ -?" q 11 t<t^l K2-l I k"'d= i(ln(f) + n}n) fl = 0, +1, +2,... 54 --- i c (Jc ' c r-t k. 1+f ko l+l k" l-l k(, Lt-: K_ -(arctan(G) + mTt) kod rr ^nr - O 55 v) 1') epsilon,myy ja kappa,[,evy 4, alfa=-5O Suhteellinen l1 Taajuus / GHz Re(er) Taajuus i,00E+10 1,10E+10 1,20E+ i0 3,67 i , 30 E +l 0 iq5 i,40E+10 I snF+ln I 6ntr+lo 'l 1,70E+10 dnR I enF+ln 4lR I OOF+IO A a1 aR 401 Im(er) -0,23 -0,22 -0,22 -0,26 -0,32 -0,31 -0,37 -0,33 -0,33 - 0 , 39 Re(pr) 0,87 0,88 0,89 0,89 0,89 0 , 88 0,87 0,86 0,86 0 , 86 cml440 56 Im(pr) 0,00 \ 0,00 0,00 0,00 0,00 0,00 0,00 0,01 0,01 0,02 Re(x) 0,38 0,29 0,23 0,20 0 ,1 9 0 ,1 7 0 ,1 6 0 ,1 5 0 ,1 4 0 ,l 3 Im(r) 0,03 0,02 0,03 0,03 0,02 0,02 0,02 0,01 -0,01 -0,02 ElectromagneticPropertiesof Losslessn-Turn Heiicesin the Quasi-Stationary Approximation LRArnautandLEDavis Department of Electrical Engineering and Electronics The Liniversity of L'lanchesterInstitute of Scienceand Technology PO Box 88, It[anchesterM60 LQD, UI{ Introduction The study of electromagnetic(EM) propertiesof bi-isotropic(BI) media at UMIST is comparatively new. It is the subject of the first author's PhD Project in Applied Biectronics. The project aims to be a '3M' approach:t mod.elling of chiral and BI media: this includesthe fundamentalstudy of the physical propertiesof generalBI media, as well as the propertiesof specificchiral structures that mav be implemented at microwave frequencies; c manufacturingol chiral and BI media: advances in the tailoring and practical imple- mentation of suspended chiral microstructures are sought; . measurement of chiral and BI media at microwave frequencies: because of the com piexity of the EM effects, new measurement techniques are considered. Advances in all three areas have been made in the recent past. In this presentation, u'e wiil discussone aspect,ie the modelling of practical chiral structures. The BN{ properties of an n-turn helix will be derived in the quasi-stationaryapproximation,its performance in terms of ENI activity wiil be predictedand comparedu'ith publisheddata. 2 Field Induced bv an n-Turn Helix Chiral propertiesofideal, short-rvirehelices,shownin Fig 1, have been derivedby Jaggard el a/. The helical structure under considerationhere is sketchedin Fig 2. The spring has n turns, free length 2/, external diameter 2c, gauge diameter 26 and pitch p : ?1. It is made of perfectiy conductingrvire and embeddedin a losslessmedium. It is assumedthat 2l ) 2a so that fringing of the magneticfield ma1'be neglected. 57 An external plane wave,characterizedby {E*, lL}, it incident onto the heiix. After some calculations,it is found that the inducedelectricfield Q is related to the induced current I bv:- E; c( c( n / A1'\ n'\-ar)' n a2 ( a; 0t;\ l-al/' rla (1) rla (2) and is directed tangential to concentriccirclesaround the helical axis. Thus, the induced electric field has a constant amplitude on concentriccircles around the helical axis, it increaseslinearly with distanceinside the helix and decreaseru. t' outside the helix. This inducedfield affectsthe fieid scatteredby the helix. In a compositemedium of u helix vol pct springsembeddedin a dielectrichost, this causesthe interactionbetweenspringsto be much larger than in a composite medium of the same vol pct u of nonchiral conducting particles. This explainswhy the BNI propertiesof dielectricswith embeddedmicrosprings changedrastically at a thresholdu : uo which is much lorverthan the classical10% limit used in multiple scatteringtheory [2]. Chiral Admittance and EM Rotation for an n-Turn Helix EM activitl' caused by chiral objects is basically an interaction between .E and H, ie a coupling betrveen the capacitance Cn and inductance Ln of a collection of chiral objects. In the quasi-static approximation, the helices are ver)' small as seen by the incident wave, hence the wave impedance of the chiral medium mav then be calculated from the lumped impedances of the helices. Compared to the idealized short helix model. inclination of the windings as well a,sinteraction between them needs to be accounted for in the model. This results in an expression for the chiral admittance of a sinsle round-wire helix:- f - t7 2l (ra)2 I_ u p( " - r ) r . s ( Zi ;M-') (3) .r\ in which e, p denote the permittivity and permeabilityof thc host medium, respectively. \\Iith appropriateaveragingover the (random) orientationof the helicesand their concentration -lV, this allows the resonancefrequencl' I 5B as rvell as the chiral admittance (. at resonanceto be calculated [1]. The results are iisted in Table 1, in whicii the computed EM rotation is compared with previously measureddata. The subscripts 1 and If refer to a singlehelix and N helices/m3,respectively. Qumtity Helix Concentration N L. Unit Ref 2 Ref 3 2.5 (at 1 0 G H z ) 2.95 (at 7 GHz) au7*' 139.8 36.7 vol To 3.2 0.8 nH/m 6.06 fF/m 93.7 89.4 I.=:]- CHz 7.13 6.84 ( € " )r p S m3 9.13 9.43 @t(J = l.))r (computed) p de8 .o74 .100 ({")N ps m3 (dr(/ = J"))w (computed) (6r(l = I.))N (mecued) (approx) 12.88 deg 425.4 42.27 NA d.g Table 1: Comparison between Predicted and Measured Data Given the fact that the information on the host material and helices is insufficient for accuratecalculationsat /" (and, therefore,dr), and taking into accountthat the computed vaiuesfor Q1serve as a lower limit due to multiple scattering,it may be concludedthat the model is sufficientlyaccurateto provide a good estimate of the EM rotation by the sample. Finally, Fig 3 showsthe dependenceof the EN{ activity of a singlehelix on its dimensions, rvhich have been normalizedwith respectto the helix length. References 1 Jaggard D L. N'IickelsonA R, Papas C ll; On Electromagnetic Waues in Chiral lIedia; Appl P h y s v o l 1 8 ( 1 9 7 9 ) ,p p 2 I L - 2 1 6 2 Guire T, Varadan V V and \"aradan Y K;EIJect ol Chimlity on Refection of Electromagnetic V'a"*esby Planar Dielectric .9lcDs;Trans IEED-EIVIC vol 32 no 4 (Nov 1990), pp 300-303 3 Hollinger R D, Varadan V V and \/aradan Y K; Etperimental chcructerization ol isotropic chiral compositesin circular war:eguides: Radio Sciencevol 25 no 2 (Mar-Apr 1992), pp 161-168 59 2b r3 rli 2! r- <i I! -l N -l ? )l /r'/;',( ) ) \\ \v / n io- a^ Figure 2 Figure1 LoglC Single (Resonance r-Turn HelLx (GHz) ) Frequency (21 = 1Om; 2bl2I LoglO (chlral for = slngl.e (s n3) ) for 21 = 10m Adnlttance 5-Turn Heltx; '01) = 1 spaclng contour -l -1 e ts. o -2. ! E o E -3. o q LogiC (Nomallzeo Ilellx Dlane!er (-) ) Ad'nLttance (s h3) ) for = '7' 2b/2'r = Single n-Turn HeLjx;24l21 Logio Loglo i , o g 1 0{ C h l r a l 'AAC) Single {NortraIlzed {chtral n-Turn Dlaneter HeIlx (s Admlllance tselLxi 2a/2i = '1' E F n E ////////t Con:o!. E "--.-]3 I E -i Conlour E SPacito _ l ffi:j c Figure3 60 spacing = 2 -2 n3) ) 2b/21 (-) ) fo! = 0001 Laboratory Repor! 128, Helsinki Electromagnelics - a w a iI n h l c o n r e n r r e s t f r o m the authors University of Technology Plane wave propagation in a uniaxial bianisotropic medium Ismo V. Lindell and Ari J. Viitanen Report 128 November1992 Abstract Uniaxial bianisotropic medium is a generalizationof the bi-isotropic and chiral media which recently have been subject to intensive research. Such a medium results, for example, when microscopicheliceswiih parallel axesare positioned in a host dielectric in random locations. Plane wave propagationin sucha medium is studied and a simple solution for the dispersionequation is found. Numerical examplesfor the wave number surfacesof the medium are displaved. I S B N9 5 1 - 2 2 - 1 3 0 3 - 6 ISSN0784-848X TKK OFPSET 61 Laboratory Electromagnetics - available on request from Report 132, the authors Helsinki University of Technology Plane wave propagation in a uniaxial bianisotropic medium with an application to a polarizatuorr transformer Ari J. Viitanen and Ismo V. Lindell Report 132 January 1993 Abstract Uniaxial bianisotropic mefium is a generalizationof the well-studied bi-isotropic and chiral rnedia. It is obtained, for example, when microscopicheliceswith parallel axes are positioned in a host dielectric in random locations. Plane wave propagation in such a medium is studied and a simple solution for the dispersionequation and for the eigenwavesare found. As a numerical glamplel polarization properties of a transverse wave propagating in a uniaxial bianisotropic medium is considered.The results give a simple possibility to construct a polarization transformer with a transverselyuniaxial chiral medium for changing the polarization of a propagating plane wave. I S B N9 5 1 - 2 2 - 1 3 8 7 - 7 ISSN0784-848X TKK OFFSET 63 Report 133, Helsinki Laboratory Electromagnetics - available frorn the authors on request University of Technology Plane-wavepropagation in a transversely bianisotropic uniaxial medium Ismo V. Lindell, Ari J. Viitanen, Piiivi K. Koivisto Report 133 January 1993 Abstract Transverselybianisotropic uniaxial medium consideredin the presentpaper can be obtained, e.8., by mixing metal heliceswith an isotropic basemedium in such a way that the axes of the helices are randomly oriented but perpendicular to a fixed direction in space. The medium is a generalizationof the well-studied chiral medium and somewhat similar to the recently stufied *i.lly bianisotropic uniaxial medium, which has interesting polarization properties. Plane wave propagation in the medium is studied and the solution for the dispersionequation is given. Numerical examplesfor the wave numbers correspondingto the two eigenwavesof the medium are displayed. It is seen that, unlike in the axially bianisotropic uniaxial medium, there are no optical axes in the present medium, in general. ISBN951-22-1393-1 ISSN0784-848X TKK OFFSET 65 Novel uniaxial bianisotropic materials SergeiA. Thetyakov,Alexander A. Sochava Radiophysics Department St. Petersburg State Technical University 195251,Polytekhnicheskaya29, St. Petersburg,Russia Recently, a novel concept of artificial composite materials with O-shaped metal elementswas introduced in [1]. The idea originated from wide and intensive studies of isotropic chiral media and their electromagneticproperties in microwave regime. A typical chiral inclusion - a small wire helix - can be consideredas an electric dipole connectedwith a magnetic dipole in such a fashion that high-frequencyelectric f.eld induces a magnetic field parallel to the original electric field component, and uice uersa. This causesoptical or microwave activity - rotation of the polarization plane of a linearly polarized propagating wave. Such chiral structures most effectively interact with circularly polarized waves, since the right and left circular polarizations are eigenpolarizationsof wavesin unbounded biisotropic media. However, one may suggestother geometrical configurations which can provide stronger wave-material interaction in other circumstanceswe deal with in microwave engineering. One of such modifications was introduced in [1], where it was suggestedto use particles shaped like the capital Greek letter O instead of chiral helical particles to ensure first-order efect on the propagation factor in a partially filled rectangular waveguide. The material can have other interesting applications [2]. In a regular microstructure with O-shapedconductiveinclusions,there exists additional interaction between electric and magnetic fields which lay in orthogonal planes, and the material can be modelledby bianisotropicconstitutiveequations. Eere we advance an idea of another modification of such microstructure configurations which can be better suited for use in plane non-reflecting coverings and antenna radomes. We focus the analysis on plane screenswhich are designedto interact with linearly polarized electromagneticwavesand suggesta modification which can provide uniform operation for linearly polarized waveswith any electric field direction (or for 67 unpolarized plane waves). This can be achievedby introducing a secondensembleof O- particlesinsidethe matrix. As a result,the structurewill interact more effectively with linearly polarized wavesof any polarization direction or with unpolarized plane lraves, Such a medium can be named as uniaxial omega-medium,becausethere exists only one particular direction - that one normal to the interfacesof a layer. The size of O-shapedelementsis assumedto be smallerthan the wavelength,hencethe medium can be describedby effective averagedmaterial parameters and the material is modelled by uniaxial bianisotropic constitutive relations which couple electric and magnetic fields. In the report we developgeneraltheory of plane wave propagation in novel media and study reflection and transmissionin plane uniaxial bianisotropic layered structures. As an example interesting for applications, we consider in detail reflection from a plane metal surface coveredwith a lossy layer. The example demonstrates that with the additional O-shapedwire elementsabsorption can be enhancedin a wide frequency range. The additional material parameter can help to manage properties of anti-reflection coatings,in a way similar to the effect provided by the chirality parameter of biisotropic materials. Another example is the reflection and transmissionthrough a plane slab. Here it is seenthat the material is perspective for potential use in antenna radomes since a nearly transparent and non-reflecting covering can be designed.Also, lossy slabs can be designedto serveas non-reflecting absorbers. It appears that the input impedance of a lossy layer on an ideally conducting surface or in free space can be matched with the free-spacewave impedance by tuning the additional coupling parameter. The impedancematching condition is frequency-independent(provided the material parameter values can be assumedto be constants) and that suggestssuperwide frequency band for prospective antireflection coveringsand antenna radomes. Designingthe material, one can compromisebetweenthe coupling parameter value, the lossesand the slab thickness. If the impedancesmatch, the thickness is essentialfor transmissionproperties,but not for the reflection. Comparing with the requirements known for chiral low- reflection screens,it seemseasier to achieve desiredeffectswith the O-composites, becausein the chiral screensrather high degree of chirality is required. 68 References [1] Saadoun,M.M.L, and N. Engheta,"A reciprocalphaseshifter using novelpseudochiral or O medium", Microwaueand Opt. Tech.Lett., Vol.5, 184-188,1992. [2] Tretyakov, S.A., "Thin pseudochirallayers: approximate boundary conditions and potential applications", Microwaueand Opt. Tech.Lett., Vol. 6, 112-115, 1993. 69 Macroscopicpredictions of material parameters for heterogeneousbi media Ari H. Sihvola Helsinki university of rechnology, Electromagnetics Laboratory Otakaari b A, 021b0Espoo, Finland In electromagnetics,we often treat materials as homogeneous, i.e. their material parameter functions are constantswith respect to space. These material parameters are macroscopic descriptions that cover all polarization and loss phenomena that take place on the microscopic physical level, and with certain restrictions, these quantities are sufficient in solving electromagneticwave problems involving maiter. rlowever, strictly taken, no media are homogeneous,at least as one rooks at them in sufficiently small scale. There are material boundaries, grain walls, etc. Media are random. Especially, as one tries to ,,seer'(and seeingis measuring the reflection or emission of electromagneticwaves) how the medium looks like, using a wavelength equal to the correlation length of the spatial permittivity function of the medium, the sceneryis kaleidoscopic:the wave behaves totally difierently than in a homogeneousmedium; it does not propagate along straight lines as the opticar wave in air but it scatters strongly, it is reflected and refracted. The macroscopic properties of dielectrically heterogeneous media have been a researchtopic for physicistsfor over a century, and studies have resulted in a wealth of mixing theories. But how about the specialguests of this workshop: ,,exotic,, materials, chiral and bi-isotropic media? Compared to classicaldielectricor magnetic materials, it is intuitively clearer that chiral media are heterogeneous. The conceptof chirality is so much connected with geometry,the handednessthat is presentat somescalewithin the microstructure of the rnaterial, that the first thought as one seesa sample of chiral material is to try to find the helical elements responsible for the chirality. An inevitable consequenceof the geometric structure is dielectric inhomogeneity in the medium. Much efrort in the chiroelectromagneticresearchof these yearsis being expended 7I on the electromagneticmodelling of a canonical chiral structure, the metal helix. There are studies of what kind of current distribution will be induced on the helix as a plane wave is incident upon it. This is not an easy problem. In the presenttalk, however,I will not considerthe emergenceof chirality through geometry. Rather, in a way of "analytically continuing" the classicaldielectric mixture rules and equations,I shall discusshow, given the chirality parametersi of the constituentsof the mixture, to predict the macroscopicchirality (and also permittivity and permeability) of the whole. In other words, in the mixture under study there are inclusionsthat are assumedto be of homogeneousbi-isotropicmaterial, and thesedeterminethe larger-scaleparameters. In this ana.lysis, the starting point is to find the polarizabilitiesof simple-shaped bi-isotropicparticles.Due to the magnetoelectriccouplingin the complexmedium, a four-elementpolarizabilitymatrix, including cross-polarizability terms, is needed. After knowing this, the classical Maxwell-Garnett and other mixing rules can be generalizedto cover bi-isotropicmedia. In appearance,theseexpand and inflate in this process,and the formulas becomecoupled: for example, the permittivity of one inclusion affects the nonreciprocity, chirality, and permeability of the mixture. The results shown in the presentationare collectedfrom my studies on biisotropic mixtures, and many illustrationshave been publishedbefore. Most results c a n b e f o u n di n t h e r e f e r e n c e[ 1 s,2,3,4,5]. some general conclusions- The salient featuresof the mixing processcan be seenalreadyfrom the simplesttwo-componentmixture: bi-isotropicspheresembedded in isotropic background medium. The coupling of all parameters was already mentioned: one macroscopicparameteris a function of all six material parameter quantities of the problem. Secondly,there exist wonderful dualities in the macroscopicmaterial formula expressions.For example,the way the permeability of the inclusion affects the effective permeability, chirality, nonreciprocity, and permittivity, is the same as the way the permittivity of the inclusion affects the effective permittivity, chirality, nonreciprocity, and permeabiiity. AIso, the functional dependenceof the macroscopicpermittivity2 on the inclusion chirality is exactly the same as on the inclusion nonreciprocity.Put into a more nonredundantform: € ^ ( e ; , p ; , r c i r X i i € rp, n ) : e ^ ( q , p ; , X ; t K ; l e n , p n ) . F u r t h e r ;t h e m a c r o s c o p i c h i r a l i t y dependson inclusion nonreciprocity identically with macroscopicnonreciprocity derend also nonreciprocity (fully biisotropic) parameters 2The same applies for the macroscopic permeability. 72 pendenceon inclusion chirality. An essential observation is the fact that the effective (:macroscopic) permittivity and permeability of a mixture are even functions of both the chirality and nonreciprocity of the component material. Hence, firstly, the sign of handedness, i.e. whether left or right handed, should not have effect on these parameters, and they are true scalars, invariant of spatial inversion. This is obvious: samples of media that are mirror images of one another should have the same permittivity and the same permeability. But such is also the dependenceon the sign of the inclusion noreciprocity parameter, although the intuitive support for this is not as evident. Also the effective chirality is an odd function of the chirality of the inclusion material (and a pseudoscalar):changing the handednessof the component changesthe handednessof the mixture. (And again, a similar conclusion holds for the effective nonreciprocity.) Furthermore, due to the fact that these functional dependencesare even, pe!turbation expansionsstart with the second-powerterm, and therefore the effect for small chiralities (and nonreciprocities)is small. In other words, the chirality of the inclusion phase has little effect on the macroscopicpermittivity and permeability, at least for high permittivity and permeability contrasts between the inclusion and background phases. On the other hand, naturally the chirality of the inclusion is the dominant parameter defining the effective chirality of the mixture. Finally, the effectivechirality of a mixture is decreasedby high permittivity and/or permeability of the inclusion phase. How, then, about inclusions of other shapes?The only other forms of inclusions whose polarizabilities can be solvedin closedform are ellipsoids. By using chiral inclusionsof ellipsoidal shapes,a further range of mixture parameters can be tailored. The effects vary: by using needle-shapedor disk-shapedinclusions, larger effective parameters can be achieved,although the shape-effectdependson the dielectric and magnetic contrast between the inclusion and host phases. One observation is, however, always valid: sphericalinclusions produce minimum effectsin the macroscopic Properties,and each deviation from this extremum shape always increasesthe value achievedby the spherical geometry. References [1] A.H. Sihvola, I.V. Lindell: Chiral Maxwell-Garnett mixing formula. Electronics 73 L e t t e r s ,V o l . 2 6 , N o . 2 , p . 1 1 8 - 1 1 9 1 , 8 t h J a n u a r y1 9 9 0 . [2] A. H. Sihvola, I. V. Lindell: Polarisability and mixing formula for chiral ellipsoids.E/eclronicsLetters,Vol. 26, No. 14, p. 1007-1009,Sth July 1990. [3] I. V. Lindell, A. H. Sihvola: Quasi-staticanalysisof scatteringfrom a chiral sphere. Journal of Electromagnetic Waaesand Applications, Vol. 4, No. 12, p. 1223-1231,1990. [a] A. Sihvola,I.V. Lindell: Analysis on chiral mixtures. Journal of Electromagnetic Waaesand Applications,Vol. 6, No. 5/6, p. 553-572,1992. [5] A. H. Sihvola: Bi-isotropic mixtures. IEEE Transactions on Antennas ond Propagation,Vol. 40, No. 2, p. 188-197,February 1992. Covariant methods in the theory of electromagneticwaves Fedor I. Fedorov BelorussianAcademy of Sciences,Institute of Physics Skarvna Str. 70. 220602Minsk. Bvelarus This presentationfocusedon the history and presentstate of crystal optics, starting from the basic works of Pockels(1906), Drude (1912), and Born (1932). The different crystal types were classifiedaccording to the symmetry and other properties of the correspondingpolarizability matrices. Optical activity and gyrotropy in crystals has received considerableattention starting from late 1950tsin Belorussia and the former Soviet Union in general. The talk discussedin detail the historical development of the constitutive relations of optically active media, as the early suggestionsby Drude and Born were shown to be inconsistent with the energy conservation principle. The material equations in the final form are nowadays labeled often Drade-Born-Fedorourelations in the Western literature. Special emphasisin the talk was given to the coordinate-freecovariant representationof quantities that appear in the electromagneticanalysis of anisotropic and bianisotropic media. (fron the uotebook oJ the l{orkshop organizer) 75 Fundamental principles resticting the macroscopicphenomenologicaldescription of matter Anatoly N. Serdyukov Gomel State University Department of Physics SovjetskayaStr. t04,246699 Gomel, Byelarus 77 Ttae- Reqrro/ Syaac/2y ht' f 0rt.,q". - et/"'" Fo,Xo xa =zKoeFe ti--zEi^ Koe= ?o?eKeo vl.rc 7o = *r/ or 7o=-/ ope.olti* f G -- l), h uqaeeltba TFe= ,ro'// f,ae -r€tn ?o Q /t/o cro su ^ia ( L in ar €?ee*ro // n a,nt ix = D,eE+dU @=[V),v") t?l + = (K*) = It;*-) LP J a.r€ /r2r.-.t6 -t? K,t aa W = ED* 48 TE=E, *l , 7Lr,s= e ,r, € r, K,, o.' Er3= t! '2t €.r --4 K,, K 4,, = -fu f,= d,z=-lzr n ot, lB ---fst = "f4 o{= e -A 4tt = -f,7, t = S Knt K^g(i wl,e.c2,,(r,...a,z ctt. or iet f ora^2ttrs,tzlattc Koe(4)= ?^7e fto(Tq) | {{,>=G,b} I f g =g , T L = - L =7e,-Di e(e,D $(e,D= f G;h) *k.h\=-E'€-n Lledia Q = €E *t4 ,otE=-6 ro*! =/ I f'=Ur+\ 0 =FE */ 4 (D t = u9, t'= UeU E= U€, ^/ p/=4q0 t- ,/= ltJltJa7 t=ltlluFil Ir t/=S isama#''r ol slnaep!,a.n vr rql 1t =s/s l rdelt'on of rgsvh/: lSl S"cS p= ls F 18 lnn 52 dasseg (ose): 3 ,f 'llreruQhna(' e/) lon aa{\.a'* F.Fyodoror q clasc 4nn E=-d (ei = 'ar,;) n2 rP: 9n*, 9+-9, f=' + - ,C !rP a + - e- t 8+ 8. C = -+, O g- 9, 9' -9, e + c ls1=-t lsl =-t lSl'+'t cl :.1 (q.9-9's) 0{cgs 42^ 4- og= &ft(q.Q* Boih'04 4 tll 6'q) *- Lz 0t d , Lr"0 4,r 0o O lo 4,t 0l Io o 0) l&,, o ol at ol f oler,sa/iort- 4 mm : $' = &,0d[ = 0 4I"n t l=144g =lla,*9.!9 'il' il=! : *ri = kar" sin0'sin19' fransfurnay'tVa a+d e,he*'ca( Srxqdr/ !tta/,9 osa'l(ofort (^, t%ay'tl ?: , al t-/ / t?e 7"!'=ry 70 f: t;- w '9 p!, inetr.f til€ EeLrr 0dt'40et '44 a'lrbJ ,:hU qa bc# E(ac sdy &no' ( r0l,lE L - 28 _sg : -- t m // / ' u - ce1 t. 2 ? 9e I,anP =fe N' l.s/H'=P'+i! 3 ; 2* le 7g,= l,E ml =-,(1-yf e/m r= +eE jyz - a2 - t'rt) 2 =€ *4nil4 g"gr A = / +4f,1/m llt = /+ rl 4rr{e2/m ' tL" -asz -itu fl a=-e_ JLz-as'- , F4; Qr \ \+ \ * JL2-col-c'fa)! , r$ i -\ X tl \ j' R T t, + n=/5n ' {^ fr 2=e € *44 A = ,PE *,,4! llo=- 4+ lz'r'rj/u ff^ t? Jt64' 4n.{ eg/n t'l&) E(e,?)= E6e,-g) T'e+e, t+-F *F, 4*-4 E D*0,9--Q a (e&) =- i(e,-g, N \,...N F,/ - ai'r, r ,' 9 / n y ' ' = 4= ea lr [/''D': P; lJ'nQ'= f, - s'€',,/'!/ JD' ,*/8, t'il \ \, + :/t't { se *u( [ 8=e€ I o =f€*,t<( 9*. Sr tl + \r = I&'' 9 o - ( relE'=-U' - ,'/ r-\ t2+ ?*: T{o ed,s7{ ld*a,a s./,qte$,) j,.n*--reg ! t{r-,r4>+ Flecl Tl,z linea. d /ta1ae/,'c F,e// on Ae /h{q.a( orl,za/ lcrty,lF D = eE * ,'dl\ g =,r! ';*€l *2"=//,',tr-',/liir\ €(U = € + tlhx *ft) = & +; f ht d({) = s^"://,uu1(ezf) {1, o e g t lv tA r* c eA rx fU)=- c r=f 'l =-fierl *, TAeT/u.crr "1 U'"*"t*f rrU A"rt"*A (l serdyutzl uin t&e#odun4rpr^o.t, SYrrq /976) 'ral €'=h (,t4r'l4'l- Lss'l) 4-- zE *ad y - €t_ + lH T. E E'= s' T F(eit';e,a) ?l t I * s*ctset.I*e:t! gI F = # {e'he - :.lt;.5.{.e:!.. T: t*-t, I=-4: g t+-t ---> - Loelee'#1 F'= # {g-*g'*--I4! e.,*te-*... _e ! U|e:.1 Fr=F -> q=qt4nN4 ?= l< 12,=z /el t = {+ 4tile <= 4rl{a l=l+4ntll f=4nilg li=[:;.1l €(e,U -- E6e,p r<(ert)=fk,-/l -Ke,-b 4k,l )= 82 an/ &ncf;ea? Dua4nfuTrat n -srh I 'rrlr2'l 'si.A e fi|l= F -t ) use {J "t)(t ril '0)l |,21 e u t4eJ | 6l' L(-): tl l- :/ .) Ji :r;'-, ;,;'-';, ,,) I: nsa)Lf ,:: { r-- (/e6?) [': L5,. , llrl[ t+O "c) eta 0 t iq0 4lt f) - si, ::,il 'i;Al E ,t0 ,l), t) et utC t 0 ss& sle0 t 2,, , tz'(e), , ,E',*'( 'rc, H, ut 'e) tf= +*,/( ,te 6(a). 4' /5', t e + (7 t+f)lut, ,a0 f)t a 0ttttt n E ^Ct-1+ ze* (€ ,-/ ,))@ @ @tc, utc t /) : O.{, a n,O u , 2 e+ (s,/''/) ,) ) *A t 4e -6, l+ -/ / ( s;^ ,E E.tta -H/ t == l -t /I +-€ r/ l=i.+ Q = €t +a.Hl E = {E */nt a/=o =ft ?:;;:f;,1 ryzs n={rr-{_fr f Particular wavesin bi-isotropic media Igor V. Semchenko Gomel State University, Department of Physics SovjetskayaStr. 704,246699 Gomel, Byelarus 85 PARTICALAR WAVESIN BI-ISOTROPIC MEDIA I.V. SEMCHENKO Investigationof the possibility of existenceand featuresof propagationof particular waves (longitudinaland helicoidal)in the magneto-activeplasmaand metalsin the magnetic field are reported in [1,2]. It is demonstrated[3] that similar waves can also exist in natural gyrotropic media within certain frequencyrangesclose to the absorptionband. The present paper results from the study of propagationand excitation of the particular waves in biisotropic media having optical properties describablewith the help of phenomenological material equations[4-7]. D=eE+Q+i$fr E=p,E+(i-igE (l) Here t, p and o are tensors of permittivity, magnetic permeability and natural optical activity, x is the tensordescribingthe mediumoptical non-reciprocal,the sign "tilde" (-) designatestransposition. Since properties of a medium in material equations (1) are characterizedby the tensorst, lL, e, x they are applicableto describethe optical behaviour of anisotropicopticallyactivenon-mutualmedia. From Maxwell's equationsfor flat waves [4] ni'E=8, rfi E=0, ri'H =-D, tn D=o (2) and materialequations(l) the wave equationfor the electricfield in thebi-isotropicmedium follows as lirttfi -riz *2i u fi.' +e v -x2 - u2i E =0 and its solutionare right-handed and left-handed circularpolarizedwaveswith the refraction index n,=Tv-:?*a (3) Here fr=ntis the refractionvector,iis a unit vectorspecifyingthe directionof propagation of waves, f is an antisymmetrictensordual to the vector fr, ttre point betweenthe vectors indicatestheir direct (double)producr. The permittivity within field frequenciescloseto the mediumabsorptionbandsmay approach zero making it possible for particular waves in bi-isotropic media to exist. When the relationship 86 eq=x', (4) field frequencyc,r,due to the is fulhlled, which is true for a certainelectromagnetic it followsfrom formula(3) that l+ : d' of the mediumparameters, frequencydispersion n : - o. In this caseonly a singlecircularlypolarizedwavewith the refractionindex in the bi-isotropicmedium: n J lo I canpropagate (5) .u, fr.ii E,=8 :e*pl,(;,a id r--co,r)l Here?and f,are singlevectorsformingthe right trio with the vectorof the wavenormalf, to the parametricsign d at the frequencyc,rr. and the circular polarizationsign corresponds as (1) and (2) the magneticfield intensityvectorH is expressed From e4uations -l H=:-lrft'E-(x-ia)El p Using it and relationship(a) for wave (5) it is obtained -l H ' p=-:- xE E , = . i a E ,' -[ D -- = - i s ^ l : E \p So, for the above wave it is obtainedthat H 10, still Umov-Pointing'svector transformsinto zero and the wave doesnot convey energy. Identical, the so-calledspiral, waves can appear also in the magneto-activepiasma [], yet they can propagateonly in the direction of an external masnetic field. Now consider the condition (6) l"1r-f=o, field closeto the which can occur within a certainfrequencyc,r,of the electromagnetic (6) is fulfilledrefractionindexes(3) acquirethe band.Whenrelationship mediumabsorption form (7) n . ( r , r 2=)2 l c ( < , l r )| , n _ ( o r r= )0 . (8) to refractionindex (7), it is wave corresponds A circularly polarizedelectromagnetic by the followingvectors characterized 87 .r,, .? - E=g "1, expg(-2lalf, i_a,t)l ./)c-l H=_:_(x+ia,)E, P - D= - -/ t'N* ( x + i a )E , l.r E=-ziuE where the circular polarization sign is determinedby the optical activity parameter sign 0(<,lt. A wave with arbitrary elipticity ? correspondsto the zero refraction index ; .- dtivE L=6 ,tt+ e -io.r ' -l p=:_(iu_x)E, l.r E=D=0. which has an infinite phase velocity and is independentof coordinates.The energy flux density vector of the wave averagedin time has the form q'Y* ' < i i >.. = - c 4n p(l*y2) Llngitudinal waves of the plasma type can also exist within the frequency co, for which condition (6) is fulfilled: E = 8fi expli(K, n-r-- o, r) l , a-=D=0. 88 (e) -1 H=_:_(x_ia)E, p The wave number K,, of the longitudinal waves can be determined by considering the second-orderthree-dimensionaldispersiontaking into account that the permittivity tensor dependsupon the wave number [1]: -yo(<o))[[ e (o,fl = eo(o)+yo(r,r)t'+(yr(r,r) (10) Thenthe waveequationof the electricalfield intensityhasthe followingform: ' r f i + 2 i u r f i ' } E = 0, { e o p - x 2 - u 2 - ( l - F o pr i)z * l l * ( g r - F o ) p l r n wherethe followingdesignations are used: go=vo9i, (11) n -., a2 Pt - It c2 c- From wave equation (11) a condition of the eiectrical field longitudinal componentfollows ( eo p- x 2- a 2* 0 # n 2 ) E rr = 0 , from which the lonsitudinal wave number is derived Klt (l)l c\ q.2*x2-eov (12) ItF In response to the parameter signp, thenon-attenuating longitudinal wavescanexisteither within the frequencyrangein which qot P,> o) a2*x2 > eov or within the frequencyrange in which (dt pr < 0) a 2 * x 2< e o v Since the energy flux densityvector of waveswith refractionindexes(7) and (8) differs from zero these waves can be excited by an electromagneticwave incident upon a bi-isotropic medium from outside. One of mechanismsexciting a longitudinalwave (9) can be the effect of Vavilov-Cherenkovwhich is discussedbelow. For this purposethe wave equationof the electromagneticfield with the sourcein the bi-isotropic medium is written as: 89 , , o t l E =_ ! l y 9 f \ r o t r o t + e p , - x z - c3z _ z t s 9 c2 ot2 c ot c2 dt' . When second-orderthree dimensionaldispersion(10) is takeninto accountthe wave equation acquires the form A2 v^ A2 "t.-,t^ p:lv.v-(r *i },ji)v' * {1r--r-:: c' dt' e o v - x 2 - qd2 c2 c' ( 13) dt" _ziag v,)r= _!lt_ 9 f dt2 c ot c2 at' Where V is a symbolic vector differential operator. In order to take into account the frequencydispersionof the medium properliesthe parameters to, F ,X, d,.yolr ShOuld - dependentoperators By writing down the be treatedas differential argument i-: currentdensityfor a pin-pointed :' charge e moving with a constantvelocity t ? j = e -v^ ', -6 ( f- i t ) , non-homogeneous equation(13) is solvedfor the Fourier-componentof the longitudinalfield: Et= - 4t peik eik(/-it) k 2 ( e o p x 2 - a 2* y J t k 2 ) Also,the solution of equation(13) with the zero right term should be taken lnto account E, =E^E eiGt-ot) Now a full solutionof equation (13) E=Er*Ey 90 satisfyingthe original condition E(f, t) =0 , at t=0 acquiresthe form (14) I -'-'(tu-o)r 4,.v-eid ,i{Er-'t), E 1 r , r l- 1rz eop-x2-o'*Yrvk' whereall the parameterscharacterizinga mediumare functionsof the argumentH Whenthe conditions e o p - x 2 - u 2+ y , p f t 2= 0 , El= a ( 15) are fulhlled field amplitude (14) increasesin time linearly: =.- . L\r,t ) = 4t ueikt den(o) k'v---:- dG) It has been assumedthat magnitudesx2,o2 and 7,k2 than eo. are less frequency-dependent From relationships(12), (15) it follows that the Cherenkovemissionof longitudinalwaves is possibleproviding v>G) g . 2* x 2 - e o l t the phasevelocityof longitudinalwavesin a i.e., whenthe velocityof an electronexceeds medium. bi-isotropic 91 REFERENCES Ginzburgv.L. Propagation of electromagnetic wavesin theplasma.Moscow,1960, pp. 108-223(in Russ.) 2. Konstantinov o.v., Perelv.I. Possibilityof magnetic wavespassage througha metal in a strongfreld.Journalof Exp. andTheor.physics,1960,Vol.38, pp. 16l-164 3. BokutB.v., Gvozdevv.v., SerdyukovA.N. particularwavesin naturalgyrotropic media.Journalof AppliedSpectroscopy, 1981,Vol.34,No4, pp. 701-706. +. A FedorovF.I. Theoryof gyrotropy.Minsk. 1979,p.456(in Russ.) 5. SihvolaA.H., LindellI.V. Bi-isotropic constitutive relations.MicrowaveandOnt. Tech.Lett.V 4, Ne8, pp.295-297, July,l991. 6. KongJ.A. Electromagnetic wavetheory.New-york:Wiley,19g6. 7. MonzonJ.c. Radiation andscattering in homogeneous generalbi-isotropic regions. IEEE Trans.Antennas Propagat., Vol. 38, Ne2, pp.227-235, Februa.yftfO. 92