A 60 GHz Code-Modulated Interferometric Imaging System Using a Phased Array

This paper presents a millimeter-wave code-modulated interferometric imaging system, which is a lens-less approach to realizing imagers using repurposed phased arrays. To use a phased array as an interferometer, incoming signals are code modulated using phase shifters, multiplexed using a power combiner, and processed through a shared receiver chain. An interference pattern is then obtained by a squaring operation, from which complex visibilities can be demodulated. Here, a four-element 60-GHz phased array chip is packaged with slot antennas, and a single 60-GHz output is measured using a power detector. This scalar measurement is then demodulated to obtain the interferometric visibilities. The four-element phased array is thinned to obtain a 13-pixel image and the system is demonstrated through a point-source detected at different locations.