Subarray processing for passive radar localization

The addition of an array to a passive radar increases the possible ways to process data for different purposes. The digital beamforming capability, used in a passive radar environment with multiple transmitters and geometries, can be used to increase gain in a particular direction, reduce signal interference in another, or to estimate the direction of a transmitting source. This paper presents a method to achieve multiple objectives simultaneously, in this case improving both detection and localization, by processing data from subsets of receiver channels at different stages. It is demonstrated using experimental data that through this scheme, a relatively small array of 6 antenna elements can further reduce direct signal interference by 35 dB in a scenario where the air target is in a near forward-scatter bistatic configuration; at the same time retaining its ability to estimate the target direction of arrival.