Microwave/Millimeter‐Wave Holography for Near‐Field Imaging Applications

This chapter discusses recent developments of microwave holography toward near‐field applications such as biomedical imaging, nondestructive testing, and underground imaging. To improve the accuracy of the holographic imaging techniques in near‐field applications, two major approaches have been presented based on: using the simulated incident field and Green's function information and using the measured point‐spread function of the imaging system. The single‐frequency 2D holographic image reconstruction developed is adapted for near‐field imaging applications. The chapter also discusses how the 2D near‐field holographic imaging technique is extended to full 3D imaging when wideband information is available. Only 2D holographic imaging results were presented employing forward‐scattered waves. The chapter extends the near‐field holographic techniques when the object is in the far zone of the antenna but the measurements are performed in the near zone of the scattering object. This algorithm employs the phaseless radiation pattern of the antenna.