Effects of channel mismatch and phase noise on jamming cancellation

Various hardware errors, including channel mismatch and phase noise, adversely affect the performance of jamming sidelobe cancellation in a digital beamforming array that combines array elements into overlapped subarrays for digital combining and uses auxiliary channels to obtain an estimate of the jammer signals. Analysis is needed to determine how much hardware error can be tolerated to obtain a desired level of jamming cancellation performance. We derive analytical, closed-form expressions that separately relate channel mismatch and phase noise to jamming cancellation ratio (CR) in a sidelobe cancellation system. We also validate our theoretical results using a high-fidelity simulation that models the phased array and signal processing chain, and obtain a close agreement between the theoretical and simulated results. By incorporating the errors in element- and subarray-level combining weights, we show that CR can be a misleading metric and it is more useful to consider the residue powers. We show that the residue power curve is proportional to the subarray pattern and provide design guidelines for improving jamming cancellation performance.