Printed Aperiodic Cavity for Computational and Microwave Imaging

We demonstrate a frequency-diverse aperture for microwave imaging based on a planar cavity at K-band frequencies (18-26.5 GHz). The structure consists of an array of radiating circular irises patterned into the front surface of a double-sided printed circuit board. The irises are distributed in a Fibonacci pattern to maximize spatial diversity at the scene. The printed cavity is a phase-diverse system and encodes imaged scene information onto a set of frequencies that span the K-band. Similar to recently reported metamaterial apertures, the printed cavity imager does not require any mechanically moving parts or complex phase shifting networks. Imaging of a number of targets is shown; these reconstructed images demonstrate the ability of the system to perform imaging at the diffraction limit. The proposed printed cavity imager possesses a relatively large quality factor that can be traded off to achieve higher radiation efficiency. The general mode characteristics of the printed cavity suggest advantages when used in computational imaging scenarios.