Direction Finding of Wideband Radar Signals with Two Rotating Antennas

Detection and direction of arrival (DOA) estimation is a signal processing challenge for wideband signals like LPI radar signals. Modern radars change theirs signal waveforms from pulse to pulse and distribute the signal in the time or frequency domain. Traditional direction finders usually use a narrowband channel to maximize sensitivity and detection range. Increasing the signal bandwidth decreases the SNR and the probability of intercept (POI). In this paper we proposed a new method for the direction finding of LPI radars, which increases the POI. In the proposed method we used two rotating antennas, one antenna used as a matched filter to the other one, in order to increase the processing gain. The proposed method despite traditional direction-finding methods, is able to detect and analyze pseudo noise and spread spectrum radar signals, without any theoretical limitation on signal frequency bandwidth. In this paper we used two antennas and proposed a new method with cross correlation technic for direction finding such as the method used in Monopulse tracking radars and compared it with other methods. Simulations shows good detection specifications for low SNR and we could reach about 25dB processing gain in wideband radar signals like LPI Radars or LFM Modulated radar signals.