Frequency selective computational through wall imaging using a dynamically reconfigurable metasurface aperture

A two-dimensional (2D) dynamically reconfigurable metasurface aperture is presented to perform frequency selective through wall imaging (TWI) with an unknown structure of the wall. Generally, in TWI, the medium properties and thickness of the wall need to be known in advance, which is not always possible. Moreover, compensating for these effects can significantly increase the computational complexity. We propose a two-stage method that leverages the concept of a dynamically reconfigurable metasurface antenna (DMA) in a narrow frequency band in which the effects of the wall are minimum to perform TWI. First, two simple probe antennas are used to evaluate the reflection response of the wall by means of a simple backscatter measurement. Based on these characteristics, a narrow band frequency selective window is identified. Second, a DMA consisting of an array of tunable metamaterial elements is used for TWI in the identified frequency selective window. The DMA aperture enables the scene information to be sampled through a set of spatio-temporally varying quasi-random modes using a single-channel transmit and receive architecture. This physical-layer compression scheme can significantly simplify the data acquisition while the quasi-random sampling of the scene information eliminates the need for conventional raster-scan based modalities.