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 sub-arrays 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.