Multistatic microwave imaging with arrays of planar cavities

The authors present a multistatic imaging system at microwave frequencies based on arrays of planar cavity sub-apertures, or panels. The cavity imager consists of sets of transmit and receive panels, loaded with radiating irises distributed over the sub-apertures in an aperiodic pattern. This frequency-diverse aperture produces distinct radiation patterns as a function of frequency that encode scene information onto a set of measurements; images are subsequently reconstructed using computational imaging approaches. Similar to previously reported computational imaging systems, the cavity-based imager presents a simple system architecture, minimising the number and expense of components required in traditional microwave imaging systems. The cavity imager builds on previous frequency-diverse approaches, such as the recently reported metamaterial and air-filled cavity systems, by utilising frequency-diverse panels for both the transmit and receive sub-apertures of the imaging system. Though the panel-to-panel architecture has greater sensitivity to calibration error, this implementation nevertheless increases mode diversity and, in the context of a computational imaging system, results in improved image reconstructions.