OFDM-based digital array radar with frequency domain mode multiplexing

Improvements in RF and digital technology have made digital array radar (DAR) feasible. The combination of orthogonal frequency-division multiplexing (OFDM) as a wideband pulse compression modulation with a DAR architecture allows time dispersion effects to be mitigated for electrically-long antenna arrays. This concept can be extended to the simultaneous operation of multiple radar modes. Each mode is allocated some number of OFDM subcarriers. The subcarriers corresponding to a particular mode are then phase-shifted to create an element-to-element phase shift across the antenna array to steer the full-aperture antenna beam for that particular mode. This concept multiplexes the modes in the frequency domain while the OFDM-based DAR allows each mode to experience the full-aperture gain on transmit and receive while being electronically steered to an independent spatial position.