Two-Way Pattern Grating Lobe Control for Distributed Digital Subarray Antennas

An approach to controlling the two-way pattern (i.e., the product of the transmitting and receiving antenna patterns) for a distributed digital subarray antenna (DDSA) is presented. Collectively combining periodic widely separated subarrays results in grating lobes (GLs), and they are unwanted because of the ambiguities that accompany them. The approach to GL control presented here involves a combination of conventional suppression methods on the transmitting side and in the digital beamforming on the receiving side, filling the gaps between the subarrays with “virtual” elements, thus forming a contiguous array. Individually, the transmitting and receiving antenna patterns may not have adequate performance, but it is demonstrated that if designed to complement each other, the two-way pattern can achieve ultralow sidelobe performance. The effects of receiving element signal-to-noise ratio (SNR) and errors in calibration are also addressed.