A guide to the applications of holographic techniques for microwave and millimeter wave imaging
Real-Time Three-Dimensional Imaging of Dielectric Bodies Using Microwave/Millimeter Wave Holography offers an authoritative guide to the field of microwave holography for the specific application of imaging dielectric bodies. The authors - noted experts on the topic - review the early works in the area of optical and microwave holographic imaging and explore recent advances of the microwave and millimeter wave imaging techniques. These techniques are based on the measurement of both magnitude and phase over an aperture and then implementing digital image reconstruction.
The book presents developments in the microwave holographic techniques for near-field imaging applications such as biomedical imaging and non-destructive testing of materials. The authors also examine novel holographic techniques to gain super-resolution or quantitative images. The book also includes a discussion of the capabilities and limitations of holographic reconstruction techniques and provides recommendations for overcoming many of the limitations. This important book:
• Describes the evolution of wide-band microwave holography techniques from synthetic aperture radar principles
• Explores two major approaches to near-field microwave holography: Using the incident field and Green's function information and using point-spread function of the imaging system
• Introduces the "diffraction limit" in the resolution for techniques that are based on the Born approximation, and provides techniques to overcome this limit
Written for students and research associates in microwave and millimeter wave engineering, Real-Time Three-Dimensional Imaging of Dielectric Bodies Using Microwave/Millimeter Wave Holography reviews microwave and millimeter-wave imaging techniques based on the holographic principles and provides information on the most current developments.
Table of Contents
Preface xi
Acknowledgments xiii
1 Introduction 1
1.1 Some Emerging Applications of MMI 2
1.2 Quantitative Versus Qualitative MMI 7
1.3 Advantages of Holographic MMI Techniques 10
1.4 Chronological Developments in the Holographic MMI Techniques 11
1.5 Future Outlook for Holographic MMI for Real-Time 3D Imaging Applications 14
2 Microwave/Millimeter Wave Holography Based on the Concepts of Optical Holography 17
2.1 Microwave Hologram Formation 18
2.2 Microwave Detectors and Sampling Methods for Intensity Hologram Measurements 20
2.3 Wave Front Reconstruction 22
2.4 Recent Indirect Holographic Imaging Techniques 24
2.4.1 Producing Reference Signal with a Linear Phase Shift 25
2.4.2 Sample Imaging Results 28
3 Direct and Quasi-Microwave/Millimeter-Wave Holography for Far-Field Imaging Applications 33
3.1 Using Microwave and Millimeter-Wave Holography for Concealed Weapon Detection 33
3.2 Monostatic 2D SAR Imaging 34
3.3 Development of 3D Quasi-Holographic Imaging as a Combination of Monostatic 2D SAR Imaging and True 2D Holographic Imaging 37
3.3.1 Single-Frequency Holographic 2D Imaging 37
3.3.2 Wideband Holographic 3D Imaging with Data Collected over Rectangular Apertures 40
3.3.2.1 Spatial and Frequency Sampling 43
3.3.2.2 Range and Cross-Range Resolution 44
3.3.2.3 Sample Experimental Images 46
3.3.3 Wideband Holographic 3D Imaging with Data Collected over Cylindrical Apertures 52
3.3.3.1 Image Reconstruction Technique 52
3.3.3.2 Sampling Criteria and Spatial Resolution 55
3.3.3.3 Image Reconstruction Results 56
4 Microwave/Millimeter-Wave Holography for Near-Field Imaging Applications 63
4.1 2D Near-Field Holographic Imaging 63
4.1.1 Using All Reflection and Transmission S-Parameters 65
4.1.2 Localization of the Object Along the Range 66
4.1.3 Image Reconstruction Results 69
4.2 3D Near-Field Holographic Imaging Using Incident Field and Green’s Function 71
4.2.1 Image Reconstruction Results 75
4.2.2 Suppressing Artifacts Along Range 79
4.3 Microwave Holographic Imaging Employing Forward-Scattered Waves Only 82
4.3.1 Resolution in a Two-Antenna Configuration 83
4.3.2 Multiple Receiver Setup 88
4.3.3 Holographic Image Reconstruction 89
4.4 Microwave Holographic Imaging Employing PSF of the Imaging System 91
4.4.1 Using Measured PSF in Holographic Reconstruction 91
4.4.2 Using Multiple Receivers in 3D Reconstruction 92
4.4.3 Simulated Image Reconstruction Results 93
4.4.4 Experimental Results with Open-Ended Waveguides 95
4.4.5 3D Imaging of Small Objects with the Bow-Tie Array 99
4.4.6 Imaging of Large Objects with the Bow-Tie Array 102
4.5 3D Near-Field Holographic Imaging with Data Acquired over Cylindrical Apertures 102
4.5.1 Imaging Results 107
4.6 Three-Dimensional Holographic Imaging Using Single-Frequency Microwave Data 109
4.7 Microwave Holographic Imaging Using the Antenna Phaseless Radiation Pattern 110
4.7.1 Using Phaseless Antenna Pattern in Holographic Reconstruction 111
4.7.2 Image Reconstruction Results 113
5 Increasing the Resolution and Accuracy of Microwave/Millimeter-Wave Holography 119
5.1 Imaging Beyond the Diffraction Limit by Applying a SOF 119
5.1.1 Design of 1D and 2D SOFs 119
5.1.2 Application of the SOF to Overcome the Diffraction-Limited Resolution 121
5.1.3 Sample Image Reconstruction Results 122
5.2 Use of Resonant Scatterers in the Proximity of the Imaged Objects 122
5.3 Quantitative Reconstruction Based on Microwave Holography 124
5.4 Modifications on Holographic Imaging Improving Stability and Range Resolution 128
5.4.1 Forward Model in Terms of the Open-Circuit Voltage at the Terminals of Probe Antenna 129
5.4.2 Applying an Auxiliary Equation for Numerical Stability 132
5.4.3 Phase Compensation Method 132
5.4.4 Numerical Low-Pass Filter in Spatial-Frequency Domain 134
5.4.5 Simulation Results 136
6 Conclusion 139
Appendix: Diffraction Limit for the Spatial Resolution in Far-Field Imaging 141
References 143
Index 153
