抽象
在本論文中，所提出操作在2.4GHz帶有頻率選擇表面的2x2陣列天線，可以獲得高增益、高效率以及高指向性，可實現增加自我注入鎖定雷達系統對生命徵象監測的靈敏度。頻率選擇表面為雙層設計，每層為9x7單元晶格。首先，作者提出耶路撒冷交叉形狀的頻率選擇表面，第二種設計是修改耶路撒冷形狀的FSS，使其在頻寬與高增益有更好的性能。天線使用FR-4基板製造，其ε_r為4.4，厚度為0.8mm，天線尺寸為20x20x27.9 cm3
在本論文中，比較了天線反射損耗、增益、輻射模式和效率的模擬與量測結果。沒有頻率選擇表面時，其增益為11dBi，效率為79%。而使用頻率選擇表面的天線陣列設計可以實現15.2dBi的增益，並具有82%的效率。因此，本論文中所設計的頻率選擇表面可以將增益提高4 dB，效率提高3%.
本論文所設計的雷達系統，包含了天線、低雜訊放大器以及正交解調器，可用以偵測人體的生命徵象。本文將進行兩種實驗，第一種為在無環境雜波干擾的條件下，比較有無頻率選擇表面時，雷達的量測結果；第二種則是在不同距離下，以木牆來分隔雷達與人體，進行生命徵象量測。藉由此高增益天線的設計來增加雷達靈敏度，使得雷達能夠量測到更遠的距離，訊號甚至能夠穿過牆壁來偵測目標。

Abstract
In this research, a 2.4 GHz phased array antenna 2x2 with frequency selective surface (FSS) is proposed to obtain high gain, high efficiency, and directivity for improving the sensitivity of vital sign monitoring using Self injection locked radar systems. The FSS designed with double layer with unit cells of 9x7 for each layer. First, the author proposed the Jerusalem cross shaped of FSS. The second design is the modification of the Jerusalem shaped FSS with outcome of a better performance with sufficient bandwidth and higher gain. The antenna is fabricated using FR-4 substrate with ε_r of 4.4 and the thickness of 0.8 mm with the dimension of the antenna is 20x20x27.9 cm3.
In this thesis, the antenna performance is evaluated as the S11, gain, Radiation Pattern and Efficiency in both simulation and measurement results. Without the FSS, the gain obtained is 11.2 dBi with the efficiency of 79%. On the other hand, the antenna array design using FSS can obtain a gain of 15.2 dBi and has better efficiency, 82%. Therefore, the FSS in this thesis can increase the gain up to 4dB and the efficiency up to 3%.
The SIL radar system consists of the antenna, low noise amplifier, and IQ demodulator to detect the subject’s vital sign including the respiration rate and heartbeat rate. The experiment for vital sign monitoring was taken in two ways. First, the experiment without any clutter environment by using antenna array with and without FSS. The other experiment conducts a vital sign monitoring through the wall in various distance such as 50 cm, 75 cm, and 100cm away from the radar systems. By designing a higher gain antenna, it can improve the sensitivity of the SIL radar system, thus it can detect the subject who is placed in further distance and even there is a wall between the SIL radar and the subject.

 

Acknowledgements 3
抽象 5
Abstract 7
Table of Content 9
List of Figures 11
List of Tables 15
Chapter 1 Introduction 17
1.1 Background 17
1.2 Motivation 18
1.3 Thesis Structure 19
Chapter 2 Antenna and SIL Radar Theory 21
2.1 Antenna 21
2.1.1 Return Loss 21
2.1.2 VSWR (Voltage Standing Wave Ratio) 22
2.1.3 Radiation Pattern 22
2.1.4 Gain 24
2.2 Theory of FSS 25
2.2.1 FSS Applications 31
2.2.2 Strip Grating Filters 31
2.2.3 Analysis of More Complex Structures: 33
2.2.4 A Brief Most Common FSS Geometries 37
2.3 SIL Radar 39
2.3.1 Self Injection Locked Radar Theory 40
Chapter 3 Design and Experiment 47
3.1 Antenna Design 47
3.1.1 Quarter wave transformer 48
3.1.2 Patch Antenna Array 48
3.1.3 Fabrication 51
3.1.4 Simulation and Measurement Results 51
3.2 Frequency Selective Surface Design 54
3.3 Combination of Antenna and Frequency Selective Surface (FSS) 57
3.3.1 Simulation and Measurement Results 60
Chapter 4 Radar SIL Measurement Results 65
4.1 Experiment of Vital Sign Detection 65
4.1.1 System Architecture 65
4.2 Vital Sign Monitoring with and without FSS 69
4.3 Vital Sign Monitoring Through the Wall without FSS 74
4.4 Vital Sign Monitoring through the wall with FSS 77
Chapter 5 Conclusion 83
REFERENCES 85

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