24 GHz Patch Antenna Array Design for RADAR

120 Pages·2016·13.52 MB·English

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Series of Master’s theses
Department of Electrical and Information Technology
LU/LTH-EIT 2016-531
Department of Electrical and Information Technology,
http://www.eit.lth.se Faculty of Engineering, LTH, Lund University, 2016.
24 GHz Patch Antenna Array Design
for RADAR
Karl Nordin
Sina Shamekhi
Department of Electrical and Information Technology
Faculty of Engineering, LTH, Lund University
SE-221 00 Lund, Sweden
Advisor:
Buon Kiong Lau
Examiner:
Mats Gustafsson
June 29, 2016
Printed in Sweden
E-huset, Lund, 2016
Abstract
Radar is a technology that is widely used in many diverse areas; from monitoring
space down to ocean surveillance, with many more applications in between. The
technology existed before, but was mainly developed in secret by several nations
during World War II. Radar technology uses radio waves to detect various kinds
ofobjectsandcandeterminetheirrange,velocityandorientation. Itis,therefore,
an very attractive technology to be used for surveillance applications.
The main goal with the thesis is to create a non-expensive, fast and efficient
people detecting device that can be used for surveillance applications. The device
should be able to detect the position of people in the area under surveillance.
Themotivationforusingradartechnologyisthatitisunaffectedbypoorweather
conditions or low visibility, unlike visual based surveillance systems.
Three different configurations of 24 GHz Frequency-Modulated Continuous
Wave (FMCW) patch antenna arrays were designed, manufactured and tested
withanexistingradar. Differentsignalprocessingalgorithms, socalledDirection-
of-Arrival (DOA) methods, were also implemented in order to process the data
from the radar. The antenna array configurations showed good results, with one
of them showing a more robust performance overall.
Keywords:
Direction-of-Arrival (DOA), Frequency-Modulated Continuous Wave (FMCW),
Patch Antenna Array, Radar
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Acknowledgments
We would like to express our gratitude for all the people that have been involved
in helping and supporting us during the work of this thesis:
Oursupervisor,ProfessorBuonKiongLauattheFacultyofEnginnering,LTH,
forhisvaluableandwisereflections,whichhavebeenveryhelpfulforfinishingthis
work.
Ourexaminer,ProfessorMatsGustafssonattheFacultyofEnginnering,LTH,
for all his helpful comments.
Alexander Bondarik, PhD student at the Faculty of Enginnering, LTH, for
helping us with the simulation software and the S-parameter measurements.
Our industrial supervisor Carl-Axel Alm for his encouragements throughout
thewholeprojectandforgivingusvaluableandhelpfulinsights,whichweneeded
and appreciate very much.
Johan Wennersten, for helping us implementing the algorithms and providing
with valuable knowledge.
Last but not least, the whole PCNI team for making our stay very enjoyable
and making us feel welcome. Thank you!
Lund, June 29, 2016
Karl Nordin & Sina Shamekhi
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Table of Contents
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Thesis Goal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Thesis Work Division . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Theory of Radar 5
2.1 Introduction to Radar Technology . . . . . . . . . . . . . . . . . . . 5
2.2 Frequency Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Pulsed Radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3.1 MaximumUnambiguousRange 7
2.3.2 RangeResolution 8
2.3.3 UsableRange 8
2.4 Continuous Wave (CW) Radar . . . . . . . . . . . . . . . . . . . . . 8
2.4.1 Frequency-ModulatedContinuousWave(FMCW)Radar 9
3 Theory of Antenna and Propagation 13
3.1 Antenna Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.1 TheFarFieldandtheNearField 14
3.1.2 Beamwidth,GainandEffectiveAperture 14
3.1.3 BandwidthandFractionalBandwidth 15
3.2 Propagation Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.1 WavePropagationParameters 15
3.2.2 TheFriisTransmissionEquation 15
3.2.3 TheRadarRangeEquation 16
3.2.4 RadarCross-Section 17
3.3 Antenna Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.3.1 AntennaArraySynthesisandDesignMethods 20
3.4 MIMO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.4.1 VirtualArray 23
3.5 Microstrip Patch Antennas . . . . . . . . . . . . . . . . . . . . . . . 25
3.5.1 InputResistance 26
3.5.2 GuidetoDesignaMicrostripFedPatchAntenna 28
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4 Range and Direction-of-Arrival Estimation Algorithms 29
4.1 The Fourier Transform . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2 Introduction to Direction-of-Arrival Algorithms . . . . . . . . . . . . 31
4.3 Array Synthesis Beamformers . . . . . . . . . . . . . . . . . . . . . 33
4.4 Adaptive Direction-of-Arrival Algorithms . . . . . . . . . . . . . . . 34
4.5 Capon/MVDR Beamformer . . . . . . . . . . . . . . . . . . . . . . 35
4.6 Subspace Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.6.1 MUSICAlgorithm 37
5 Software and Hardware Tools 39
5.1 Computer Simulation Technology (CST) . . . . . . . . . . . . . . . 39
5.2 INRAS Radarbook Description . . . . . . . . . . . . . . . . . . . . . 40
5.3 Verification of the Signal Processing Algorithms . . . . . . . . . . . 42
5.3.1 ImplementationofDirection-of-ArrivalAlgorithms 46
5.3.2 VerificationofDirection-of-ArrivalAlgorithmsUsingINRASFrontend 47
6 Proposal of Antenna Array Design 53
6.1 Azimuth-Elevation Visualization . . . . . . . . . . . . . . . . . . . . 53
6.2 Proposed Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
7 Simulation Results of Antenna Array Element 61
7.1 Design of 24 GHz Single Patch Antenna. . . . . . . . . . . . . . . . 61
7.2 Design of 4x1 Linear Patch Antenna Array . . . . . . . . . . . . . . 65
7.2.1 FeedingNetwork 65
7.3 Final Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
7.3.1 FirstDesignConfiguration 66
7.3.2 SecondDesignConfiguration 66
7.3.3 ThirdDesignConfiguration 66
7.3.4 FinalDesignConfiguration 68
7.4 Simulation of 24 GHz Single Patch Antenna . . . . . . . . . . . . . 68
7.5 Simulation of 4x1 Linear Patch Antenna Array . . . . . . . . . . . . 70
8 Measurement Results 75
8.1 Manufactured Patch Antenna Arrays . . . . . . . . . . . . . . . . . 75
8.2 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
8.3 Measurement of S-Parameters . . . . . . . . . . . . . . . . . . . . . 79
8.4 Tests with Direction-of-Arrival Algorithms . . . . . . . . . . . . . . . 81
8.4.1 TestScenarioOne 82
8.4.2 TestScenarioTwo 87
9 Discussion 93
9.1 Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
9.2 Measurement Results . . . . . . . . . . . . . . . . . . . . . . . . . . 94
9.3 Direction-of-Arrival Algorithms. . . . . . . . . . . . . . . . . . . . . 95
9.3.1 ImplementationofMIMO 96
9.3.2 CovarianceMatrixEstimationProblemsandImplications 96
10 Conclusions 97
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11 Further Work 99
References 101
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