臺灣博碩士論文加值系統

本論文提出了結合探針補償之微波全像術，採用擁有稍高增益的探針天線進行平面掃描式近場成像。首先由探針天線發射入射場至待測之散射物，再由該探針接收因散射物造成散射場，利用平面上不同位置收集到的散射場資訊進行微波成像。選用高增益探針天線進行研究是因為它可以降低散射場過弱而不易量測的難度。為了讓成像品質更好，我們額外考慮了探針的輻射特性以及其環境，進而將它們補償。本研究結合探針天線補償以及微波成像，除了理論推導外，並以模擬和實驗驗證。
在模擬方面，採用FEKO電磁模擬軟體進行一系列成像示範，並探討空間取樣率對成像品質的影響。在實驗方面，我們架設了一套成像系統，選用操作在X波段的微帶天線當作探針進行量測。除了前述利用單天線進行量測的系統外，我們亦考慮更適合量測薄弱散射場的準單天線系統。

A novel probe-compensated microwave holographic imaging method is proposed. Planar scanning by a directive probe antenna is adopted to reconstruct the images of unknown metallic or dielectric targets. Unknown targets are first illuminated by the probe antenna, and then the fields scattered from the targets are received by the probe. Directive or moderate-gain probe antennas are adopted since they are more sensitive to the scattered fields. To enhance the image quality, the proposed approach necessitates the detailed radiation information of the probe antenna and its environment. Theoretical formulation for image reconstruction is derived and verified by both simulations and experiments.
A series of imaging results based on FEKO simulations is presented to verify the efficacy of the proposed imaging approach. The effects of sampling rate on the image reconstruction are also investigated. Moreover, the experimental imaging system is also built up. A microstrip patch antenna that operates at X-band is chosen as the moderate-gain probe antenna. In addition to the monostatic imaging system, a quasi-monostatic system is also demonstrated. The quasi-monostatic system is more feasible and is capable of measuring the relatively weak fields scattered from dielectric targets.

致謝 i
中文摘要 ii
ABSTRACT iii
CONTENT iv
LIST OF FIGURES vi
LIST OF TABLES x
Chapter 1 Introduction 1
1.1 Research Background 1
1.2 Motivation and Methodology 2
1.3 Chapter Outline 3
Chapter 2 Probe-Compensated Holographic Imaging 4
2.1 Introduction 4
2.2 Response of a Receiving Antenna with an Exterior Source 5
2.3 Planar Scanning with Arbitrary Probe Antennas 8
2.4 Discussions on the Image Reconstruction Equation 12
2.4.1 Metallic Scatterers 12
2.4.2 Probe-Compensation Mechanisms 13
2.4.3 Comparison with the Uncompensated Approach 15
Chapter 3 Simulation Results and Parameter Survey 17
3.1 The Simulation Tool 17
3.2 Simulation Results with Probe-Compensated Technique 18
3.2.1 Using a Patch Antenna as the Probe 18
3.2.2 Using a Half-Wavelength Dipole Antenna as the Probe 23
3.2.3 Metallic Scatterers 28
3.3 Discussions on the Scanning Configuration 32
3.3.1 Comparison of a Patch Antenna and a Half-wavelength Dipole Antenna 32
3.3.2 Sampling Rate 34
Chapter 4 Holographic Imaging Systems and Measurement Results 39
4.1 Holographic Imaging Systems 39
4.1.1 System Descriptions 39
4.1.2 Probe Antennas 42
4.1.3 Scanning Setups 45
4.2 Image Results 47
4.2.1 The Monostatic System 47
4.2.2 The Quasi-monostatic System 51
Chapter 5 Conclusions 54
5.1 Summary 54
5.2 Future Work 55
Reference 56

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