Design of Compact Antenna with modified ground plane for

IPASJ International Journal of Electronics & Communication (IIJEC)
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Email: [email protected]
ISSN 2321-5984
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Volume 3, Issue 3, March 2015
Design of Compact Antenna with modified
ground plane for ultra wide band
communication
Suchita Borkar1, Minal A. Mishra2
1
2
Laxmi Institute of Technology, Sarigam
Vadodara Institute of Technology, Kotambi
ABSTRACT
In this paper, T shaped antenna for ultra wide band communication is designed. Both the antennas have modified ground
planes. The designed antenna is T-shaped antenna. The results of antenna have shown VSWR of 1.2 for the return loss of -40
dB at the operating frequency of 7.5 GHz. HFSS-11 software is used for the simulation of the antennas.
Keywords: UWB, compact antenna, modified ground plane, T-shaped antenna.
1. INTRODUCTION
In February, 2002, the FCC(federal communication commission) permitted UWB operation and UWB devices FCC’s
spectrum allocation for UWB is from 3.1 GHz to 10.6 GHz. UWB has the high data rate transmission nearly of 500
Mbps. UWB is employed for Short range applications. Its distance range is 10 meters. The power spectral density of
UWB are very low -41.3 dBm/MHz[1]. The antennas are divided into two groups. They are directional and omnidirectional antennas. The Directional antennas are narrow band antennas since Their beam is focused wich requires
very high gain. Whereas the omni- directional antennas are called as wideband antenna as they radiates in all the
directions. The UWB antennas have broad band. UWB systems can be implemented with small size, low cost and low
power on the single chip architecture. There are many challenges in UWB antenna design. One of the challenge is
to achieve wide impedance bandwidth . UWB antennas are typically required to attain a bandwidth, which reaches
greater than 100% of the center frequency to ensure a sufficient impedance match is attained throughout the band such
that a power loss less than 10% due to reflections occurs at the antenna terminals. Aside from attaining a sufficient
impedance bandwidth, linear phase is also required for optimal wave reception, which corresponds to near constant
group delay. This minimizes
pulse distortion during transmission. Also, high radiation efficiency is required especially for UWB applications. Since
the transmit power is so low (below the noise floor), power loss due to dielectrics and conductor losses must be
minimized. Typically, antennas sold commercially achieve efficiencies of 50-60% due to lossy dielectrics. The physical
constraints require compatibility with portable electronic devices and integrated circuits. The VSWR of the designed
antenna should be less than 2 and the return loss should be less than -10 dB within operating bandwidth
2. DESIGN PROCEDURE
STEP 1: CALCULATION OF THE WIDTH (W ): THE WIDTH OF THE MICROSTRIP PATCH ANTENNA IS GIVEN BY EQUATION
AS:
Step 2: Calculation of Effective dielectric constant (εreff ): Equation gives the effective dielectric constant as:
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IPASJ International Journal of Electronics & Communication (IIJEC)
Web Site: http://www.ipasj.org/IIJEC/IIJEC.htm
Email: [email protected]
ISSN 2321-5984
A Publisher for Research Motivation........
Volume 3, Issue 3, March 2015
Step 3: Calculation of the Effective length (L eff ): Equation gives the effective length as:
Step 4: Calculation of the length extension (ΔL ): Equation gives the length extension as:
Step 5: Calculation of actual length of patch ( L ): The actual length is obtained by re-writing equation as:
3. ANTENNA CONFIGURATION AND DESIGN
The geometry, parameters, top and side views for a prototype of the proposed planar T- shaped antenna are shown in
Figure 1. The antenna consists of modified grpound structure.T-shaped antenna is printed on the top side of the
substrate and two slot s are printed on opposite sides of substrate that is on ground plane. The planar arms parallel to
x-y plane; micro strip line is along the y-axis. 50 ohm microstrip line is used for design of the proposed antenna.
(a)
(b)
(c)
Figure 1 Geometry of compact antenna with modified ground plane for UWB communication (a) Top View (b)
Bottom View (C) Design geometry
Top view and front view of T- shaped patch antenna are indicated in figure2. The proposed antenna was designed on a
Rogers RT/duroid 5880TM substrate with dielectric constant εr = 2.2 and height of the substrate is h =0.894 mm. The
substrate has length L= 32mm and width W=28.1mm.The substrate is mounted on ground of 32 mm length and 28.1
mm width. The antenna diamensions are W= 12.45mm, Ls= 2.5mm, Ws= 1mm, L= 7.5mm, Groundcut1=28.1X5mm2
Ground cut 2= 28.1X8mm2 .
Volume 3, Issue 3, March 2015
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IPASJ International Journal of Electronics & Communication (IIJEC)
Web Site: http://www.ipasj.org/IIJEC/IIJEC.htm
Email: [email protected]
ISSN 2321-5984
A Publisher for Research Motivation........
Volume 3, Issue 3, March 2015
Figure 2 Current distribution of antenna with modified ground plane at 7.5 GHz
Figures 3 and 4 denotes the VSWR and S11 respectively of the proposed patch antenna. The results shows the absolute
bandwidth of 2.4GHz. The fractional bandwidth of 2.5G/7.5G=33% of the centre frequency is obtained.
Figure 3 VSWR of patch antenna with modified ground plane
Figure 4 S11 of patch antenna with modified ground plane
Radiation Pattern 16
Ansoft Corporation
HFSSModel1
0
-30
Curve Info
rETotal
Setup1 : LastAdaptive
Phi='0deg'
30
9.60
rETotal
Setup1 : LastAdaptive
Phi='10deg'
7.20
-60
60
4.80
rETotal
Setup1 : LastAdaptive
Phi='20deg'
2.40
-90
90
rETotal
Setup1 : LastAdaptive
Phi='30deg'
rETotal
Setup1 : LastAdaptive
Phi='40deg'
-120
120
-150
rETotal
Setup1 : LastAdaptive
Phi='50deg'
150
-180
(a)
Volume 3, Issue 3, March 2015
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IPASJ International Journal of Electronics & Communication (IIJEC)
Web Site: http://www.ipasj.org/IIJEC/IIJEC.htm
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ISSN 2321-5984
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Volume 3, Issue 3, March 2015
Radiation Pattern 19
Ansoft Corporation
HFSSModel1
0
-30
Curve Info
dB(DirTotal)
Setup1 : LastAdaptive
Phi='0deg'
30
-2.00
dB(DirTotal)
Setup1 : LastAdaptive
Phi='10deg'
-9.00
-60
60
-16.00
dB(DirTotal)
Setup1 : LastAdaptive
Phi='20deg'
-23.00
-90
90
dB(DirTotal)
Setup1 : LastAdaptive
Phi='30deg'
dB(DirTotal)
Setup1 : LastAdaptive
Phi='40deg'
-120
120
-150
dB(DirTotal)
Setup1 : LastAdaptive
Phi='50deg'
150
-180
(b)
Figure 5 Radiation pattern of antenna with modified ground plane at 7.5GHz
4.CONCLUSION
In this paper, the antenna with modified ground plane is simulated using HFSS. The proposed antenna has the
advantages of small size, easy fabrication and simple construction. The simulated results of proposed antenna for return
loss is less than -10 dB and VSWR of less than 2 can be obtained at the operating frequency of 7.5 GHz. The antenna is
suitable for ultra- wideband communication.
References
[1] Zhi Ning Chen, Xuan Hui Wu, Hui feng li, Ning Yang , and Michael yan Wah Chia,” Considerations for source
pulses and antennas in UWB system”,IEEE 2004
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[7] Sang-Gyu Kim and K. Chang “Ultra wideband exponentially-tapered antipodal Vivaldi antennas” IEEE
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[13] K. S. Yngvesson, D. H. Schaubert, T. L. Korzeniowski, E. L. Kollberg,T. Thungren, and J. F. Johansson, “Endfire
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