Through‐wall microwave imaging system using circularly polarised spiral antenna array

A new three‐dimensional through‐wall imaging (TWI) system is implemented for short range sensing. The system is equipped with a circularly polarised antenna array to improve image quality and reduce the wall artefacts. It consists of an array of 19 antennas positioned hexagonally. The array delivers half‐space radiation with wideband performance, necessary for imaging applications. A differential tomographic imaging algorithm is developed to create through‐wall images via both coherent and non‐coherent processes. The imaging system has some advantages to traditional synthetic aperture radar approaches and other linear fixed aperture systems. It has a modular structure, uses both co‐polarised and cross‐polarised waves, capable of sensing conductive objects hidden behind dielectric layers (wall). The experimental results confirm that the new TWI system can create images of conductive objects hidden behind a dielectric wall clearly.