EHF Rotman Lens Fed Linear Array Multibeam Planar Near

EHF Rotman Lens Fed Linear Array Multibeam Planar Near

EHF Rotman Lens Fed Linear Array
Multibeam Planar Near-Field Range
Measurements
CST 5th NORTH AMERICAN USERS’ FORUM
4th FEBRUARY 2008 SANTA CLARA, CA
3:40 pm - 4:05 p.m.
Mike Maybell
Planet Earth Communications LLC
1983 San Luis Ave. #31
Mountain View, CA
94043-2900
650-965-7456
[email protected]
John Demas
Nearfield Systems Inc.
19730 Magellan Drive
Torrance, CA 90502
AGENDA
2/4/2008
• Rotman Lens-True Time Delay Beamformer
• Rotman Lens Application Example
• Rotman Lens CST MWS Analysis
• Rotman Lens Analysis vs. Measurements
• AMTA Paper A07-0090 Presented 11/6/07
1A
Rotman Lens Physical Optics Design
•
2/4/2008
Rotman1 lens parameters
•
Four basic parameters; α, β, γ, f1
¾ TEM transmission line lengths w computed using Rotman
& Turner formulas
•
•
The focal arc is a circle defined by Rotman & Turner
formulas
The beam pointing angles are frequency independent
y
L2
Parameter
y3
y2
α
β
(X2,y2)
L1
w
Ψ
f2
3 focal
points
α
f1
x
γ
Ψm
f1
d
Na
Nb
εr
Definition
Focal Angle
Focal Ratio
Beam to Ray Angle Ratio
Maximum Beam Angle
Focal Length
Array Element Spacing
Number of Array Ports
Number of Beam Ports
Rel. Dielectric Constant
Formula
f2/f1
sinΨ/sinα
Note: γ is the compression factor if <1
γ is the expansion factor if <1 >1
[1] Rotman, W. and Turner, R. F., “Wide-Angle Microwave Lens for Line Source Applications,” Trans. IEEE, Vol. AP-11, Nov. 1963, pp. 623-632.
1B
Rotman Lens Application: AN/SLQ-32(V)
AN/SLQ-32(V)2 Outboard Array Enclosure
•
SLQ-32 is the primary EW
suite used on over 450 US
Navy Ships.
•
Each ship has one port and
one starboard antenna
enclosure equipped with a
Band 2 receive, Band 3
Sidekick Transmitter
receive, and Band 3
transmit (V)3 pair of
quadrant linear sectoral
horn arrays fed by Rotman
lenses providing 360°
instantaneous azimuth
coverage.
•
2/4/2008
Thus there are 12 Rotman
lenses per (V)3 ship set.
AN/SLQ-32 Band 3 Rotman Lens Fed
Receive Array Measured Multibeam Rosette
AN/SLQ-32 Band 3 Receive Rotman Lens Fed Array
1C
EHF Rotman Lens CST MWS Analysis
•
In 2005 when analysis was
required, available CST
hardware & software was
marginal
•
Using Dell Precision
Workstation with 16 GB
RAM, A planar array was
successfully analyzed using
CST MWS TDS in Oct. 2007
• 8801 cubic wavelengths
• 40.6 M mesh cells
•
Acceleware ClusterInABox™
D30WL should help make
CST MWS solution practical
2/4/2008
14”
17”
0.41”
Fmax
45.5 GHz
L
λ
W
17.00 inch
L/λ
65.54
LWH/λ3 =
14.00 inch
W/λ
53.97
0.26 inch
H
0.41 inch
H/λ
1.58
5590.3 cubic wavelenghts
9.9 M mesh cells
1D
EHF Rotman Lens TE Mode Lens MultiPort S-Matrix Analysis
• We selected TE1 and
TE2 mode contour
integral lens analysis2 in
conjunction with CST
MWS modeling of the
isolated waveguide tees
including TE1/TE2
mode coupling due to
resistance card and
other asymmetries
within the tees
• The results3 compared
well with measured lens
data
2/4/2008
TE1 Mode
TE1/TE2 Mode
44.5 GHz
Composite Beams 1-44 TE1/TE2 Overlay
44.5 GHz
[2] A. F. Peterson and E. O. Rausch, “Scattering matrix integral equation analysis for the design of a waveguide Rotman lens,” IEEE Trans. Antennas Propagat., vol. 47, pp. 870-878, May 1999
[3] M. J. Maybell et al, “EHF Waveguide Rotman Lens for Minimum Frequency Scan and Low Loss Design, Analysis, Test,” Paper #2215 submitted to 2008 IEEE International
Symposium on Antennas and Propagation & 2008 USNC/URSI National Radio Science Meeting
1E
ABSTRACT
Objective
• Measure Realized gain for 44 beam 44 element linear array
•
•
Single column of 50 column multibeam 2200 element planar active
receive array for geostationary satellite communications payload
•
•
•
1760 simultaneous 0.4 degree beams/1463 earth beams
Multibeam single prototype column realized gain tested at the Nearfield
Systems Inc.'s (NSI) facility using a 12’ x 12’ Planar Near-Field Range
Two linear array configurations tested using same WR-19 waveguide fed
44 beam 44 element Rotman lens and integrated RF distribution network
(RFD).
•
•
•
•
43.5 to 45.5 GHz
Active receive array utilizing only the center 8 array elements of the Rotman
lens feed
Passive 44 element array demonstrating narrow 0.4 degree half power
beamwidth
Summary & examples of the NFR test results presented
Compared with that predicted using the previously measured lens array
factor gain (AFG) and CST computed embedded element realized gain
2
Introduction
•
•
•
•
•
•
•
•
EHF uplink array for TSAT spiral applications
Beamformers for satellite payloads create
simultaneous high gain pencil beams feeding
2200 element rectangular planar arrays from
geostationary orbit
Beamformers use column and row 2D
Rotman lens stacks feeding elements in an
equilateral triangular lattice
Equilateral triangular beam lattice covering
the entire 17.4º earth disc with 1760 “pixel”
beams
At each lens stack beam port, a 0.4° HPBW
“pixel” beam is formed with frequency
independent beam pointing angle due to
Rotman lens true time delay
RF Beam switch/combiner results in 64
simultaneous independent communication
beams
18 dB/K minimum G/Ts
• Constant communication beam pointing
angles over the full bands
Performance can be easily scaled, resulting
in reduced size weight and prime power
3
EHF Uplink 2200 Element Active Planar
Array Design Goals
Receive Active Array Design Goals
Parameter
Receive Array Size
Aperture Length
Aperture Width
Aperture Payload Depth
Column Spacing
Number Array Elements
Array Beam Performance
Operating Frequency (min.)
Operating Frequency (max.)
Peak Gain
Half Power Beamwidth
Number Pixel Earth Beams
Number Simultaneous Comm. Beams
FOV Radius (Geo)
Value
Receive Active Array Design Goals
Units
35.5
34.9
60
2.6
2200
inch
inch
inch
λ
43.5
45.5
52.2
0.4
1463
64
8.5
GHz
GHz
dBi
Degree
Degree
Parameter
Element Aperture Efficiency
Element FOV Relative Gain (min.)
Array G/T Performance
LNA
RF Loss before LNA
LNA Noise Figure
Peak G/T at 0.0 deg. Scan
Peak G/T at max. Scan
EOC beam box G/T at max. scan
Array Power And Weight
DC Power
Dissipation
Weight
Value Units
85 %
-1.5 dBi
0.5 dB
2 dB
21 dB/K
19.55 dB/K
18 dB/K
850 Watt
850 Watt
630 lbs
4
Active 8 Element/44 Beam Array &
Passive 44 Element/44 Beam Array Tested
HPFL/
Extension
Pyramidal
Horn
LNA
0.086” Semi-Rigid Coax
WR-19/2.4mm
End Launch
Transition
Rotman lens/RFD
WR-19 Shim
EHF Active Uplink Array 8 Element
RF Chain and Lens/RFD
44 Element Passive Array & lens/RFD at NSI
NFR with Mounting Fixture & Near Field Probe
5
Predicted Realized Gain Formulation
Realized gain (GR) was predicted using the previously measured lens array
factor gain (AFG) and computed embedded element realized gain (GE)
A
G R (θ ) = ∑ G E (θ )S
n =1
nB
e
j
n 2πd
λ
sin(θ )
(1)
SnB : measured lens/RFD transmission S parameter from beam port B to array port n
d/λ = 2.6 and low coupling therefore isolated and embedded element gain equal
A
G R (θ ) = G E (θ )∑ S nB e
j
n 2πd
λ
sin(θ )
n =1
G
R
(θ ) = G E (θ ) AFG (θ )
GR(θ) dBi = GE(θ) dBi + AFG(θ) dB
(2)
(3)
(4)
IEEE Std 145-1983:….When ..radiation patterns of ..array elements are
identical….product of the array factor and the element radiation pattern gives the
radiation pattern of the entire array
6
Pyramidal Horn Element CST Computed
and NFR Measured Realized Gain
Pyramidal Horn Element CST MWS Computed
Realized Gain E-Plane Radiation Pattern
20
CST MWS
Model
1.79”
15
10
R ealized G ain (d B iL )
5
0
0.791”
-5
43.5 GHz E-Plane Realized Gain (dBiL)
0.648”
-10
45.5 GHz E-Plane Realized Gain (dBiL)
-15
-20
-25
70.00
60.00
50.00
40.00
30.00
20.00
0.00
10.00
-10.00
-20.00
-30.00
-40.00
-50.00
-60.00
-70.00
-30
18.7
Angle From Boresight (deg)
18.65
CST H-Plane Radiation Pattern
20
18.6
18.55
15
18.5
10
Gain (dBiL)
18.45
0
18.4
18.35
18.3
18.25
-5
18.2
43.5 GHz H-Plane Realized Gain (dBiL)
-10
CST MWS Computed Realized Gain (dBiL)
18.15
45.5 GHz H-Plane Realized Gain (dBiL)
-15
NFR Measured horn 7 (dBiL)
18.1
NFR Measured horn 8 (dBiL)
18.05
-20
18
43.5
-25
43.7
43.9
44.1
44.3
44.5
44.7
44.9
45.1
45.3
Frequency (GHz)
Angle From Boresight (deg)
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
-10.00
-20.00
-30.00
-40.00
-50.00
-60.00
-30
-70.00
R ealized G ain (dB iL)
5
7
45.5
CST MWS Computed E-Plane Realized
Gain GE(θ) Used for Realized Gain
Prediction
To Compute Realized Gain of the 8 Element Active Array & 44 Element Passive
Array Integrated with the Rotman lens/RFD
•CST MWS computed E-Plane element realized gain GE(θ) dBi in (4)
•Measured lens array factor AFG(θ) dB using HP8510C ANA
•Required Data at 44 beam peak angles from -8º to +8º
Pyramidal Horn Element NFR Measured –
CST Computed Realized Gain Difference Statistics
Two Horn S/N’s & 220 Data Points
Pyramidal Horn Element NFR Measured - CST Computed Realized Gain
44 Beam Port F (GHz)
Angles
43.50
Mean
MAX
MIN
P-P
1 sigma
-0.150
-0.097
-0.188
0.091
0.028
F (GHz) F (GHz) F (GHz) F (GHz)
44.00
44.50
45.00
45.50
-0.027
0.172
-0.116
0.287
0.080
-0.130
0.074
-0.405
0.480
0.128
0.170
0.299
0.101
0.198
0.060
0.059
0.151
-0.082
0.233
0.062
5 Frq
-0.015
0.299
-0.405
0.480
0.072
8
Eight Element Lens/RFD Active Array NFR
Test Results; AFG(θ) Used for Realized
Gain Prediction
8 element active array integrated with
lens/RFD & S-parameters measured
with HP8510C ANA
•Array Factor computed
•13 Beam Ports: B02, B06, B10,
B14, B18, B22, B23, B27, B31,
B32, B35, B39, and B43
•8 element active Array Factor rosettes
computed
•HPBW for the 8 element active
beams is about 2º
•HPBW for the 44 element passive
beams is 0.4º due to the 5.5 x passive
array aperture
Array Factor Calculated Lens/RFD 8 Element
Active Rosette at 44.5 GHz 13 Beam Ports
9
8 Element Active Array lens/RFD
Calculated and NFR Measured Realized
Gain
•
8 Element Active Array lens/RFD
Calculated and NFR Measured
Realized Gain overlay for the same
13 beam ports as those computed
for AFG(θ) dB in previous slide.
• GR(θ) dBi =GE(θ) + AFG(θ)
(Slide 7) (Slide 9)
Calc Bench(---), vs. Meas NFR( _ ) 44.5 GHz 13 BP
Gain Statistics
8 Elt Active Array ([NFR Measured Realized Gain]
-[AF + CST MWS Computed Horn Gain])
13 Beam Port F (GHz) F (GHz F (GHz) F (GHz) F (GHz)
Angles
43.50 44.00 44.50
45.00
45.50
5 Frq
Mean
MAX
MIN
P-P
1 sigma
0.048
1.640
-0.860
1.269
0.271
-0.548
-0.113
-0.860
0.747
0.259
-0.429
0.128
-0.853
0.980
0.234
-0.141
0.379
-0.492
0.871
0.241
0.952
1.640
0.371
1.269
0.343
0.404
1.097
0.072
1.025
0.279
10
Eight Element Active Array lens/RFD
Measured Realized Gain at NSI NFR 44.5
GHz for all 44 Beam Ports
HPFL/
Extension
Pyramidal
Horn
LNA
0.086” Semi-Rigid Coax
WR-19/2.4mm
End Launch
Transition
Rotman lens/RFD
WR-19 Shim
EHF Active Uplink Array 8 Element
RF Chain and Lens/RFD
11
44 Element Lens/RFD Passive Array NFR
Test Results; AFG(θ) Used for Realized
Gain Prediction
44 element passive array
integrated with lens/RFD & Sparameters measured with
HP8510C ANA
•Array Factor computed
•All 44 Beam Ports
•44 element passive Array
Factor rosettes computed
•HPBW for the 44 element
passive beams is 0.4º as
expected
Array Factor Calculated Lens/RFD 44 Element
Passive Rosette at 44.5 GHz 44 Beam Ports
12
44 Element Passive Array & Lens/RFD
Tested for realized gain using a NSI Planar
12’x12’ NFR.
Gain for All 44 Beam Ports was Measured
13
44 Element Passive Array lens/RFD
Calculated and NFR Measured Realized
Gain
44 Element Passive Array
lens/RFD Calculated and NFR
Measured Realized Gain overlay
for all 44 beam ports as for AFG(θ)
dB in slide 12
• GR(θ) dBi =GE(θ) + AFG(θ)
(Slide 7) (Slide 12)
Calc Bench(---), vs. Meas NFR( _ ) 44.5 GHz 44 BP
Realized Gain (dBiL)
•
Gain Statistics
44 Elt Passive Array ([NFR Measured Realized Gain]
-[AF + CST MWS Computed Horn Gain])
44 Beam Port F (GHz) F (GHz) F (GHz) F (GHz) F (GHz)
Angles
43.50
44.00
44.50
45.00
45.50 5 Frq
Mean
MAX
MIN
P-P
1 sigma
0.214
0.598
-0.144
0.742
0.164
0.103
0.441
-0.278
0.719
0.170
0.299
0.572
-0.274
0.847
0.173
0.454
1.022
0.142
0.879
0.177
0.573
0.902
0.229
0.673
0.188
0.329
1.022
-0.278
0.879
0.174
14
44 Element Passive Array lens/RFD
Calculated and NFR Measured Realized
Gain
Realized Gain (dBiL)
Realized Gain (dBiL)
44 Element Passive Array lens/RFD Calculated and Measured Realized Gain
Overlay Bench (dashed lines), NFR (solid lines) 43.5 GHz & 45.5 GHz 44 Beam Ports
15
NFR Measurement Accuracy
The NFR testing was performed at
Nearfield Systems Inc., Torrance,
CA on 5/8/07 - 5/11/07, using their
Planar 12’ x 12’ NFR
• Considered Error Sources
• Gain Standard Uncertainty
¾ Considered Largest Source
¾ Calibrated at PSNA
• Impedance Mismatch Factor
• Peak Far-Field Peak Amplitude
for Gain Standard
• Multiple Reflections between
the horn and probe
• Truncation of the near-field data
for the standard gain horn
• Bias error leakage within the
receiver
• Room scattering
RF Source
Multiplier
Coupler
Probe
AUT
Pad
Test
Mixer
Test IF
x4
11.25 GHz
45.0 GHz
-10 dB
LO
LO
Ref
Mixer
Ref IF
LO to Ref
LO Source
LO/IF Unit
LO to Test
15.00667 GHz
Ref
Mixers operate in
3rd harmonic mode
Sig
Panther Receiver
Receiver displays Sig/Ref
NFR RF Test Block Diagram
Probable Uncertainties in Peak Far-Field Gain
Term
dB
Gain Standard 0.20
Mismatch
0.05
SGH FF Peak 0.15
Total (RSS)
0.25
16
Summary
• Primary emphasis of this paper was to
compare the accuracy of predicting the
realized gain using fundamental array theory
with NFR measurements
• An 8 element active array and a 44 element
passive array were both tested
• The mean gain difference between model
and measured data is 0.048 dB for the active
array and 0.329 dB for the passive array
• Overall NFR peak gain measurement
accuracy is estimated as 0.25 dB
17