Design considerations for a dynamic metamaterial aperture for computational imaging at microwave frequencies

We investigate the imaging capabilities of a one-dimensional, dynamic, metamaterial aperture that operates at the lower part of K-band microwave frequencies (17.5-21.1 GHz). The dynamic aperture consists of a microstrip transmission line with an array of radiating, complementary, subwavelength metamaterial irises patterned into the upper conductor. Diodes integrated into the metamaterial resonators provide voltage-controlled switching of the resonant metamaterial elements between radiating and nonradiating states. Applying a series of on/off patterns to the metamaterial resonators produces a series of distinct radiation patterns that sequentially illuminate a scene. The backscattered signal contains encoded scene information over a set of measurements that can be postprocessed to reconstruct an image. We present a series of design considerations for the dynamic aperture, as well as a series of experimental studies performed using a dynamic aperture prototype. High-fidelity, real-time, diffractionlimited imaging using the prototype is demonstrated. The dynamic aperture suggests a path to fast and reliable imaging with low-cost and versatile hardware, for a variety of applications including security screening, biomedical diagnostics, and through-wall imaging.