beam steering control system for low-cost phased array weather radars

220 Pages·2017·8.83 MB·English

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Doctoral Dissertations Dissertations and Theses
Fall August 2014
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Rafael H. Medina-Sanchez
University of Massachusetts Amherst
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Medina-Sanchez, Rafael H., "BEAM STEERING CONTROL SYSTEM FOR LOW-COST PHASED ARRAY
WEATHER RADARS: DESIGN AND CALIBRATION TECHNIQUES" (2014). Doctoral Dissertations. 117.
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BEAM STEERING CONTROL SYSTEM FOR LOW-COST PHASED
ARRAY WEATHER RADARS: DESIGN AND CALIBRATION
TECHNIQUES
A Dissertation Presented
by
RAFAEL H. MEDINA SANCHEZ
Submitted to the Graduate School of the
University of Massachusetts Amherst in partial fulfillment
of the requirements for the degree of
DOCTOR OF PHILOSOPHY
May 2014
Electrical and Computer Engineering
(cid:13)c Copyright by Rafael H. Medina Sanchez 2014
All Rights Reserved
BEAM STEERING CONTROL SYSTEM FOR LOW-COST PHASED
ARRAY WEATHER RADARS: DESIGN AND CALIBRATION
TECHNIQUES
A Dissertation Presented
by
RAFAEL H. MEDINA SANCHEZ
Approved as to style and content by:
David J. McLaughlin, Chair
Stephen J. Frasier, Member
Ramakrishna Janaswamy, Member
Gopal Narayanan, Member
Christopher V. Hollot, Department Chair
Electrical and Computer Engineering
This dissertation is dedicated to my wife, Michelle,
my children Jeshua, Annia and Sharai,
and my wonderful parents Carmen and Rafael.
ACKNOWLEDGMENTS
Completing my dissertation has been a tremendous personal achievement, which would
not have been possible without the support and contribution of many people. I would first
like to express my deepest gratitude to my adviser Dr. David McLaughlin, who gave me
the opportunity to be a part of CASA project and who supported in every moment the
initiative of a “CASA phased array radar”. I would like to thank Eric Knapp for his help
in discussing the technical aspect of the project and overall guidance. I also wish to thank
my good friend Jorge Salazar for developing the passive array and his enormous help in the
assembly and testing of the phased array.
I would also like to extend my gratitude to Dr. Steve Frasier, Dr. Ramakrishna
Janaswamy, and Dr. Gopal Narayanan for serving as my committee members. My spe-
cial thanks to Dr. Frasier for his involvement and valuable contribution in the solid state
radar group. I also want to thank Dr. Daniel Schaubert for teaching me all the technical
background about phased array and for facilitating the anechoic chamber to measure the
antenna.
I am thankful for the help and support of all members of CASA organization, Susan
Lanfare, Janice Brickley, Marci Kelly, and Apoorva Bajaj, who provided all the technical
and administrative support to the project.
My gratitude also goes to all members of the Microwave Remote Sensing Laboratory
for all their support. My special thank to my friend Jorge Trabal for being a valuable
source of information and discussion on radars. I thanks all my friends and colleagues
from MIRSL, especially, Vijey Venkatesh, Krzysztof Orzel, Cristina Llop, Robert Palumbu,
Razi Ahmed, Benjamin St. Peter, Mauricio Sanchez, Tony Hopf, Anthony Swochak, and
Pei Sang. Thanks to Linda Klemyk and Tom Harley for their assistance in administrative
activities and with laboratory equipments.
v
Most important, I would like to thank my family, because if it was not for them, I would
never have made it this far. My wife Michelle and children Jeshua, Annia, and Sharai,
for their love, support, encouragement, and sacrifices during all these years. My mother,
Carmen,whobelievedinmeanddideverythingshecouldtosendmetoaprivateuniversity.
I also thank her for giving me her love and instilling in me the importance of education and
hard work. My father, Rafael, for helping my mother and always being present to help me
with whatever I needed. How fortunate I am to have them in my life. I dedicate all my
achievements to them.
The work presented in this dissertation was supported primarily by the Engineering
Research Centers Program of the National Science Foundation under NSF Cooperative
Agreement No. 0313747. Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author and do not necessarily reflect those of the
National Science Foundation.
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ABSTRACT
BEAM STEERING CONTROL SYSTEM FOR LOW-COST PHASED
ARRAY WEATHER RADARS: DESIGN AND CALIBRATION
TECHNIQUES
MAY 2014
RAFAEL H. MEDINA SANCHEZ
B.E.E., UNIVERSIDAD TECNOLOGICA DE BOLVAR
M.Sc., UNIVERSITY OF PUERTO RICO MAYAGUEZ
Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST
Directed by: Professor David J. McLaughlin
Phase array antennas are a promising technology for weather surveillance radars. Their
fast beam steering capability offer the potential of improving weather observations and ex-
tending warning lead times. However, one major problem associated with this technology
is their high acquisition cost to be use in networked radar systems. One promising tech-
nology that could have a significant impact in the deployment of future dense networks
of short-range X-band weather radars is the “Phase-Tilt Radar”, a system that uses a
one-dimensional phase scanned antenna array mounted over a tilting mechanism. This
dissertation addresses some of specific challenges that arise in designing and implement-
ing air-cooled, low-cost, one-dimensional phased antenna arrays for phase-tilt radars. The
goal of this work is to develop methods that can lead to reduce the cost and enhance the
performance of this type of systems.
Specifically, the thesis focuses on three concrete areas. The first one is on the develop-
ment of a versatile low-cost beam steering system that can enable dual-polarimetric phased
array radars to operate with high-frequency repetition pulses, difference pulsing schemes,
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andmodernscanningstrategies. Inparticular,thedissertationwillpresentthedevelopment
of critical components and describes the concept of operations of the beam steering system.
The second area is to develop a calibration technique for small phased arrays. The
work focused in finding the calibration settings for the array that best fit to the desired
excitation. The technique provides lower random errors than conventional approaches,
enabling the implementation of radiation patterns with sidelobes closer to the desired level.
Additionally, the technique is extended to solve the gain-drift problem occurring in the
two-way antenna pattern due to the temperature changes.
The third area studies the use of mutual coupling as signal injection technique to main-
tain the calibration of both array and radar. Future air-cooled phased array radars will
require the use internal circuitry to calibrate the aspect of the radar that tends to change
over time. In particular, this work is focused on developing low-cost calibration techniques
to correct the antenna gain and radar constant from effects of temperature changes and
element failures.
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TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS................................................... v
ABSTRACT............................................................... vii
LIST OF TABLES.........................................................xiii
LIST OF FIGURES ....................................................... xv
CHAPTER
1. INTRODUCTION........................................................1
1.1 Introduction ...........................................................1
1.2 Problem Statement .....................................................5
1.3 Dissertation Contributions...............................................6
1.4 Dissertation Overview...................................................8
2. FUNDAMENTALS OF PHASED ARRAYS ............................ 10
2.1 Introduction ..........................................................10
2.2 Linear Array..........................................................10
2.2.1 Directive Gain..................................................12
2.2.2 Realized Gain ..................................................13
2.2.3 Half-Power Beamwidth ..........................................14
2.2.4 Half-Power Beamwidth for Two-Way Patterns ......................15
2.2.5 Gain of Active Beamformers......................................16
2.2.6 Total Power Gain of Active Phased Arrays .........................17
2.3 Radar Systems........................................................19
2.3.1 Radar Equation for Point Target Return ...........................20
2.3.2 Weather Radar Equation ........................................21
3. BEAMFORMER AND BEAM STEERING CONTROL SYSTEM...... 23
3.1 Introduction ..........................................................23
3.2 System Overview......................................................25
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