Demonstration of space-time adaptive processing for DSI suppression in a passive radar

Passive radar uses illuminators of opportunity instead of a dedicated radar transmitter. A number of already transmitted signals can be used, however, their nature is mostly continuous and their utilization is a complicated task. One of the key limiting factors of passive radar is the strong direct signal interference (DSI), even though many physical and signal processing countermeasures have already been developed. In the case of using terrestrial signals for airborne target detection, elimination of a certain elevation angle of arrival is a possible solution. As the real-world environment is non-stationary, adaptive methods are expected to give better results. The paper shows and compares two space-time adaptive vertical antenna array processing methods for DSI mitigation, applied in terrestrial navigation signal based radar. In addition, both methods are verified by processing signals captured under real-world conditions. Both methods offer more than 10 dB DSI suppression.