No abstract

SUMMARYRecently, with rapid proliferation of mobile communication, there has arisen a need for adaptive array antennas that can automatically control the antenna radiation pattern. In adaptive array antennas based on the MMSE (Minimization of Mean Square Error) method, a reference signal with a high correlation with the desired wave is required in order to distinguish the desired wave and the interference waves. The unique word (UW) employed for synchronization in mobile communication is a known signal sequence and can be used as a reference signal. However, it is necessary to accurately estimate the timing at which the UW is contained in the communication signal. The estimation error in the case of strong interference can be a cause of deterioration of the interference suppression capability. Also, if the UW is contained in both the interference and the desired wave at the same timing, the desired wave cannot be recognized and the interference wave cannot be suppressed. In this paper, an adaptive array antenna with a two-stage configuration using a preprocessing of an SLC (sidelobe canceler) is proposed so that the effect of the interference prior to the start of communication is avoided. By the simulation, it is confirmed that only the interference wave can be suppressed effectively even if the UWs contained in the interference and the desired wave are in synchronization.

No abstract

No abstract

Derivation of monopulse angle accuracy for phased array radar to achieve Cramer-Rao lower bound is presented in this paper. Antenna element positions originating from antenna center are used for difference beam taper in this monopulse angle estimation. For uniform linear array, the accuracy is 1.16 times higher than conventional monopulse method. In other words, SNR can be reduced by 1.3 dB to achieve required angle accuracy. Suboptimal difference beamforming taper for the subarray-based digital beamforming radar is also derived.