realization of a planar low-profile broadband phased array antenna

120 Pages·2010·6.38 MB·English

REALIZATION OF A PLANAR LOW-PROFILE
BROADBAND PHASED ARRAY ANTENNA
DISSERTATION
Presented in Partial Fulfillment of the Requirements for
the Degree Doctor of Philosophy in the
Graduate School of The Ohio State University
By
Justin A. Kasemodel, M.S., B.S.
Graduate Program in Electrical and Computer Engineering
The Ohio State University
2010
Dissertation Committee:
John L.Volakis, Co-Adviser
Chi-Chih Chen, Co-Adviser
Joel T. Johnson
ABSTRACT
With space at a premium, there is strong interest to develop a single ultra wide-
band(UWB)conformalphasedarrayaperturecapableofsupportingcommunications,
electronic warfare and radar functions. However, typical wideband designs transform
into narrowband or multiband apertures when placed over a ground plane. There-
fore, it is not surprising that considerable attention has been devoted to electromag-
netic bandgap (EBG) surfaces to mitigate the ground plane’s destructive interference.
However, EBGs and other periodic ground planes are narrowband and not suited for
wideband applications. As a result, developing low-cost planar phased array aper-
tures, which are concurrently broadband and low-profile over a ground plane, remains
a challenge.
The array design presented herein is based on the infinite current sheet array
(CSA) concept and uses tightly coupled dipole elements for wideband conformal op-
eration. An important aspect of tightly coupled dipole arrays (TCDAs) is the capac-
itive coupling that enables the following: (1) allows field propagation to neighboring
elements, (2) reduces dipole resonant frequency, (3) cancels ground plane inductance,
yielding a low-profile, ultra wideband phased array aperture without using lossy ma-
terials or EBGs on the ground plane. The latter, is of course, critical for retaining
the aperture’s wideband behavior under conformal installations.
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This dissertation focuses on the realization of wideband phased array apertures
using tightly coupled dipole arrays. A methodology for designing planar apertures is
presented including: element selection, material loading, and unbalanced to balanced
conversionforwidebandfeeding. Multiplesolutionsandpracticaldesignexamplesare
presented to increase bandwidth, reduce height, avoid common mode excitation and
retain low-cost planar PCB manufacturability. Using one of these designs, a 64 ele-
ment low-profile X-band array prototype is fabricated and measured. The conformal
array is capable of scanning up to 70◦ and 60◦ in the E- and H-planes, respectively.
The active VSWR is less than 2 from 8 to 12.5 GHz (1.6:1) and the array height is
only λ/7 at the lowest frequency of operation. A unique feature of the proposed array
is its planar layered PCB construction. Specifically, a single microwave laminate is
used for the aperture while another supports all associated baluns and matching net-
works. Goodagreementbetweensimulationsandmeasurementsconfirmtheproposed
concepts.
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Dedicated to my family.
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ACKNOWLEDGMENTS
I would like to express my sincere appreciation to my advisor, Professor John
L. Volakis, for his guidance and advice. Not only has he taught me the academic
side of electromagnetics and engineering, but also the importance of communication
about what it takes be a successful professional and leader. His guidance and support
led me to present at conferences, publish papers and write proposals. I would also
like to sincerely thank my Co-Advisor Dr. Chi-Chih Chen for interesting discussions
and insight on antenna design, research methodology and measurement techniques.
He has been a great friend, mentor and truly is an antenna and electromagnetics
expert. Dr. Chen showed me different ways to approach a research problem and
the steps necessary to accomplish any goal. His honesty, intelligence and open door
policy has made the ElectroScience Lab a wonderful workplace and home for the
last four years. I want to thank the other students in the Volakis antenna group for
their challenging questions, interesting discussions and sharing their research during
our weekly meetings. In addition, I want to specifically thank my colleges and close
friends; KennethE.Browne,MustafaKuloglu,BrandanT.StrojnyandOrbayTuncay
for their collaboration, proof reading, support and suggestions.
v
VITA
September 2, 1984 ..........................Born - Gillette, Wyoming
May, 2006 ..................................B.S. Electrical and Computer Eng.,
South Dakota School of Mines and
Technology, Rapid City, SD
August, 2009 ...............................M.S. Electrical and Computer Eng.,
The Ohio State University, Columbus,
OH
September, 2006 - present .................. Graduate Research Fellow,
The Ohio State University, Columbus,
OH
PUBLICATIONS
Journal Publications
1. Kasemodel, J.A.; Chen, C.-C.; Volakis, J.L., “Wideband Planar Array with
Integrated Feed and Matching Network for Wide-Angle Scanning,” Under review:
Trans. Antennas and Propagation, IEEE.
2. Kasemodel, J.A.; O’Brien, A.; Gupta, I.J.; Chen, C.-C.; Volakis, J.L., “Small,
Conformal Adaptive Antenna of Spiral Elements for GNSS Receivers,” Under review:
Trans. Antennas and Propagation, IEEE.
3. Kasemodel, J.A.; Volakis, J.L., “A Planar Dual Linear Polarized Antenna with
Integrated Balun,” To appear in Antennas and Wireless Propagation Letters, IEEE.
4. Kasemodel, J.A.; Chen, C.-C.; Gupta, I.J.; Volakis, J.L., “Miniature Continuous
Coverage Antenna Array for GNSS Receivers,” Antennas and Wireless Propagation
Letters, IEEE, vol.7, no., pp.592-595, 2008.
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Conference Publications
1. Kasemodel, J.A.; Chen, C.-C.; Volakis, J.L., “Low-profile Wideband Phased
Array Antenna with Integrated Balun,” Submitted to: Phased Array Symposium,
IEEE, Baltimore, MD, Nov., 2010.
2. Kasemodel, J.A.; Chen, C.-C.; Volakis, J.L., “Low-Cost, Planar and Wideband
Phased Array with Integrated Balun and Matching Network for Wide-Angle Scan-
ning,” in Proc. Antenna and Propagation International Symposium, IEEE, Toronto,
Ontario, Canada, July 2010.
3. Volakis, J.L.; Kasemodel, J.A.; Chen, C.-C.; Sertel, K.; Tzanidis, I., “Wideband
Conformal Metamaterial Apertures,” in Proc. Antenna Technology (iWAT), 2010
International Workshop on , vol., no., pp.1-4, 1-3 March 2010.
4. Kasemodel, J.A.; Chen, C.-C.; Volakis, J.L., “Wideband Conformal Array with
Integrated Feed and Matching Network for Wide-angle Scanning,” in Proc. URSI
National Radio Science Meeting, Boulder, CO, January, 2010.
5. Kasemodel, J.A.; Chen, C.-C.; Volakis, J.L., “A Novel Non-symmetric Tightly
Coupled Element for Wideband Phased Array Apertures,” in Proc. Antennas Appli-
cations Symposium, Allerton, IL, Sept. 2009.
6. Kasemodel, J.A.; Chen, C.-C.; Volakis, J.L., “A Miniaturization Technique
for Wideband Tightly Coupled Phased Arrays,” in Proc. Antennas and Propagation
Society International Symposium, Charleston, SC, June 2009.
7. Kasemodel, J.A.; Chen, C.-C., “A Measurement Setup for Characterizing An-
tennaonanInfiniteGroundPlanefrom1to18GHz,” inProc. Antenna Measurement
Technique Association Symposium, Boston, MA, November 2008.
8. Kasemodel, J.A.; Chen, C.-C.; Gupta, I.J.; Volakis, J.L., “Miniature Continu-
ous Coverage Wideband GPS Antenna Array,” in Proc. Antennas and Propagation
Society International Symposium, San Diego, CA, July 2008.
9. Kasemodel, J.A.; Chen, C.-C.; Gupta, I.J.; Volakis, J.L., “Compact Wideband
Antenna Array for GNSS Receivers,” in Proc. Antenna Measurement Technique As-
sociation Symposium, St. Louis, MO, November 2007.
FIELDS OF STUDY
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Major Field: Electrical Engineering
Studies in:
Applied Electromagnetics
Antenna Design and Measurement Techniques
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TABLE OF CONTENTS
Page
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Dedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Vita . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
Chapters:
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Motivation, Challenges and Objective . . . . . . . . . . . . . . . . 1
2. Broadband Phased Array Aperture using Tightly Coupled Dipoles . . . . 5
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Planar Phased Array Antenna Comparison . . . . . . . . . . . . . . 6
2.2.1 Input Impedance . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.2 Scan Element Pattern . . . . . . . . . . . . . . . . . . . . . 13
2.3 Equivalent Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4 Linear and Dual Linear Polarization Properties . . . . . . . . . . . 23
2.5 Feeding Network Consideration . . . . . . . . . . . . . . . . . . . . 27
2.5.1 External 180◦ Hybrid . . . . . . . . . . . . . . . . . . . . . 29
2.5.2 Low Cost Partially Balanced Coaxial Cable Feed . . . . . . 31
2.5.3 Impedance Matching . . . . . . . . . . . . . . . . . . . . . . 33
2.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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3. Broadband Phased Array Antenna Miniaturization . . . . . . . . . . . . 37
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.2 Antenna Miniaturization Concept . . . . . . . . . . . . . . . . . . . 38
3.3 Inductive Loading via Volumetric Meandering . . . . . . . . . . . . 39
3.4 Ferrite Substrate Loading . . . . . . . . . . . . . . . . . . . . . . . 41
3.5 Capacitive Loading using a Non-Symmetric Element . . . . . . . . 45
3.6 Dielectric Superstrate Loading . . . . . . . . . . . . . . . . . . . . 53
3.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4. Realization of Non-Symmetric Tightly Coupled Dipole Arrays . . . . . . 61
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.2 Wideband Balun . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.3 Integration of Aperture and Feed . . . . . . . . . . . . . . . . . . . 63
4.4 Single Feed Demonstration . . . . . . . . . . . . . . . . . . . . . . 65
4.5 64 Element Array Demonstration . . . . . . . . . . . . . . . . . . . 71
4.5.1 Scan Element Pattern . . . . . . . . . . . . . . . . . . . . . 71
4.5.2 Mutual Coupling and Scan Impedance . . . . . . . . . . . . 75
4.5.3 Fully Excited Radiation Performance . . . . . . . . . . . . . 83
4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
5. Conclusion and Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 93
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
x