Research on interference suppression of passive radar based on antenna beam focusing

In passive radar system utilizing non-cooperative illuminator, the interference of direct signal and multi-path clutter heavily degrades the radar system performance. The usually applied time-domain adaptive filtering method is, according to certain optimal criterion, by using reference signal, to establish multi-path channel model, and to cancel the interference of echo signal. However, interference channel varies during the rotation of antenna, which breaks the convergence of the adaptive canceller output, and degrades the ability of interference cancellation. In this paper, it is proposed that through weighting compensation to every antenna element, the beam forming is equivalent to focusing effect. Within cumulative time, the channel characteristic was kept, and the performance under radar scanning of adaptive canceller was improved. Simulations and field experiment are carried out, which proves that the method can increase interference cancellation ability of passive radar time domain adaptive canceller in antenna rotation state.