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.