S.N. Kireev

Usage of a digital active phased array (APHAR) increases radar efficiency in a passive mode. It allows forming multiple receiving antenna patterns and refusing an azimuth scanning. In an active mode the similar work at low range when it is no need in maximal signal power. It is possible to transmit signal with wide pattern antenna, to form multiple receiving antenna patterns and to search target without scanning after processing of one impulse packet. When transmitting antenna pattern is wide the signal power in a point of target is low, and it can be used for eliminating of energetic redundancy to provide secretive work. The disadvantage of the method is decreasing of antenna selectivity because of antenna pattern forming for receiving only. It is important in presence of power passive interference. In this paper the method of agile search of target in radar, based on usage in all channels of its digital APHAR deferent probing signals with low level of mutual correlation, is discussed. It provides irradiation of all targets within antenna array element beam width and provides detection of all targets after one impulse packet processing. The circuit of optimal signal detector against the noise background is justified. Matched filter mounted in the circuit, implements code division of signals. It lets to form transmitting antenna pattern for every direction and recreate spatial selectivity of APHAR. The method can be implemented in digital APHAR in which transmitting channels are assembled on direct digital synthesis generator. It is performed comparison with known method of agile search of target, based on scanning with large beam width antenna pattern and compressing its antenna pattern during impulse packet processing. The usage of receiving antenna with large beam width antenna pattern reduces antenna gain. It reduces the signal-to-noise ratio, maximal range of target detection and possibilities of radar secretive work in comparison with proposed method.