Sparse Sequential Single-Input–Multiple-Output Array Design for Ultra-Wideband Radar

This letter investigates the array design methods of the sequential single-input–multiple-output (SSIMO) array. Antennas of SSIMO array are both transmitters and receivers, and when one antenna transmits, others receive. Compared with the widely used multiple-input–multiple-output (MIMO) array, SSIMO array has the similar azimuth resolution but lower grating lobe level (GLL). As a general rule, periodic and irredundant (PIR) ultra-wideband one-way array provides a means of improving the azimuth resolution and lowering the GLL. Based on this principle, we first propose the design method for the SSIMO array with four antennas. However, if the number of antennas exceeds four, the effective array of the SSIMO array cannot be PIR. But we have successfully proposed a novel design method to deal with this problem. The simulation results and design example verify the correctness and effectiveness of the proposed method.