Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas

127 Pages·2017·9.12 MB·English

University of South Carolina
Scholar Commons
Theses and Dissertations
2017
Wideband Low Side Lobe Aperture Coupled Patch
Phased Array Antennas
Dhruva Poduval
University of South Carolina
Follow this and additional works at:http://scholarcommons.sc.edu/etd
Part of theElectrical and Computer Engineering Commons
Recommended Citation
Poduval, D.(2017).Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas.(Master's thesis). Retrieved from
http://scholarcommons.sc.edu/etd/4144
This Open Access Thesis is brought to you for free and open access by Scholar Commons. It has been accepted for inclusion in Theses and Dissertations
by an authorized administrator of Scholar Commons. For more information, please [email protected].
WIDEBAND LOW SIDE LOBE APERTURE COUPLED
PATCH PHASED ARRAY ANTENNAS

by

Dhruva Poduval

Bachelor of Engineering
Fr. C. Rodrigues Institute of Technology, University of Mumbai, 2010

Submitted in Partial Fulfillment of the Requirements

For the Degree of Master of Science in

Electrical Engineering

College of Engineering and Computing

University of South Carolina

2017

Accepted by:

Mohammod Ali, Director of Thesis

Grigory Simin, Reader

Cheryl L. Addy, Vice Provost and Dean of the Graduate School
© Copyright by Dhruva Poduval, 2017
All Rights Reserved.
ii
ACKNOWLEDGEMENTS
I am very grateful to my thesis advisor Dr. Mohammod Ali for his patience,
advice and encouragement throughout this endeavor. Without his support this research
would not have been possible.
I would also like to thank my colleague Dr. Chamok Nowrin Hasan for all the
help and assistance that he provided me with when I just started working on this thesis. I
have got to learn a great deal from him.
Lastly, I would like to thank my parents for all their blessings and financial
support which has enabled me to attend graduate school.

iii
ABSTRACT
Low profile printed antenna arrays with wide bandwidth, high gain, and low Side
Lobe Level (SLL) are in great demand for current and future commercial and military
communication systems and radar. Aperture coupled patch antennas have been proposed
to obtain wide impedance bandwidths in the past. Aperture coupling is preferred
particularly for phased arrays because of their advantage of integration to other active
devices and circuits, e.g. phase shifters, power amplifiers, low noise amplifiers, mixers
etc. However, when designing such arrays, the interplay between array performance
characteristics, such as gain, side lobe level, back lobe level, mutual coupling etc. must
be understood and optimized under multiple design constraints, e.g. substrate material
properties and thicknesses, element to element spacing, and feed lines and their
orientation and arrangements with respect to the antenna elements. The focus of this
thesis is to investigate, design, and develop an aperture coupled patch array with wide
operating bandwidth (30%), high gain (17.5 dBi), low side lobe level (20 dB), and high
Forward to Backward (F/B) ratio (21.8 dB). The target frequency range is 2.4 to 3 GHz
given its wide application in WLAN, LTE (Long Term Evolution) and other
communication systems. Notwithstanding that the design concept can very well be
adapted at other frequencies.
Specifically, a 16 element, 4 by 4 planar microstrip patch array is designed using
HFSS and experimentally developed and tested. Starting from mutual coupling
minimization a corporate feeding scheme is designed to achieve the needed performance.
iv
To reduce the SLL the corporate feeding network is redesigned to obtain a specific
amplitude taper. Studies are conducted to determine the optimum location for a metallic
reflector under the feed line to improve the F/B. An experimental prototype of the
antenna was built and tested validating and demonstrating the performance levels
expected from simulation predictions. Finally, simulated beam scanning in several angles
of the array is shown considering specific phases for each antenna element in the array.
v
TABLE OF CONTENTS
ACKNOWLEDGEMENTS ........................................................................................................ iii
ABSTRACT .......................................................................................................................... iv
LIST OF TABLES .................................................................................................................. ix
LIST OF FIGURES ...................................................................................................................x
CHAPTER 1: INTRODUCTION ..................................................................................................1
1.1 MOTIVATION FOR WORK .......................................................................................1
1.2 OVERVIEW OF THESIS ............................................................................................2
CHAPTER 2: APERTURE COUPLED PATCH .............................................................................4
2.1 INTRODUCTION ......................................................................................................4
2.2 SLOT FED PATCHES ...............................................................................................5
2.3 DESIGN AND OPTIMIZATION OF SINGLE ELEMENT APERTURE
COUPLED PATCH ANTENNA ..................................................................................7
2.4 DESIGN OF SINGLE ELEMENT PATCH ANTENNA ..................................................15
CHAPTER 3: LINEAR AND PLANAR ARRAY ANTENNAS .......................................................18
3.1 INTRODUCTION ....................................................................................................18
3.2 THE ARRAY FACTOR ...........................................................................................18
3.3 FOUR ELEMENT LINEAR ARRAY ..........................................................................22
3.4 4X4 PLANAR ARRAY ANTENNA ..........................................................................28
CHAPTER 4: ANTENNA ARRAY FEED NETWORKS ...............................................................35
vi
4.1 INTRODUCTION....................................................................................................35
4.2 THE CORPORATE FEED NETWORK.......................................................................36
4.3 4X4 ARRAY WITH INCREASED SEPARATION AND
CORPORATE FEED NETWORK ..............................................................................47
CHAPTER 5: REDUCING SIDE LOBE AND BACKLOBE LEVELS IN PLANAR ARRAYS ..............50
5.1 INTRODUCTION....................................................................................................50
5.2 BINOMIAL ANTENNA ARRAYS ............................................................................51
5.3 DOLPH-CHEBYSHEV ANTENNA ARRAYS .............................................................54
5.4 SYNTHESIZING ARRAY FACTORS ........................................................................58
5.5 AMPLITUDE TAPERED CORPORATE FEED ............................................................61
5.6 REDUCING BACKLOBE RADIATION .....................................................................67
CHAPTER 6: FABRICATION AND MEASUREMENT OF ARRAY ...............................................75
6.1 INTRODUCTION....................................................................................................75
6.2 FABRICATION ......................................................................................................76
6.3 MEASUREMENT RESULTS FOR 4X4 ARRAY .........................................................81
6.4 MEASUREMENT RESULTS FOR 4X4 ARRAY WITH REFLECTOR .............................86
6.5 MEASUREMENT RESULTS FOR 4X4 ARRAY WITH SUPERSTRATE .........................89
6.6 MEASUREMENT RESULTS FOR 4X4 ARRAY
WITH REFLECTOR AND SUPERSTRATE .................................................................92
CHAPTER 7: PHASED ARRAY ...............................................................................................96
7.1 INTRODUCTION....................................................................................................96
7.2 BEAM STEERING .................................................................................................96
CHAPTER 8: CONCLUSION AND FUTURE WORK ................................................................105
8.1 CONCLUSION .....................................................................................................105
vii
8.2 FUTURE WORK ..................................................................................................106
REFERENCES .....................................................................................................................108
viii
LIST OF TABLES
Table 2.1 Antenna parameters ...........................................................................................15
Table 3.1 Summary of simulation results for linear array .................................................27
Table 3.2 Summary of simulation results for individually fed planar array antenna ........34
Table 4.1 Summary of simulation results for individually fed planar array antenna with
increased separation ...........................................................................................................46

Table 4.2 Summary of simulation results for planar array antenna fed using a corporate
feed .....................................................................................................................................49

Table 5.1 Summary of radiation pattern data for binomial array ......................................54
Table 5.2 Summary of radiation pattern data for Dolph-Chebyshev array........................57
Table 5.3 Summary of radiation pattern data for synthesized array ..................................61
Table 5.4 Summary of radiation pattern data for array with tapered corporate feed .........67
Table 5.5 Simulation data for the 4X4 array with metal reflector .....................................74
Table 6.1 Measured data for 4X4 array .............................................................................85
Table 6.2 Measured data for 4X4 array with reflector.......................................................88
Table 6.3 Measured data for 4X4 array with superstrate ...................................................92
Table 6.4 Measured data for 4X4 array with superstrate and reflector .............................95
Table 7.1 Summary of radiation pattern data with main beam at θ = +10𝑜,Φ = 90𝑜 ..100

ix