Next-Generation SF-STAR

Next-Generation SF-STAR Compared to frequency-division and time-division duplexing (FDD and TDD), same-frequency, simultaneous transmit and receive (SF-STAR) can increase the spectral efficiency of a full-duplex communication link by a factor of two. Efficient use of spectrum is becoming a high priority due to government mandates and signaling environments that are becoming more contested and congested, particularly on the battlefield. But for reliable communication, SF-STAR systems must control by passive or active means, the self-interference that occurs when signals from high-power transmitters couple into sensitive receivers. A next-generation SF-STAR system is described that operates over a broad range of carrier frequencies (DC-80 GHz), processes wideband waveforms (> 1000 MHz), utilizes all-digital beamforming, and realizes a transmit/receive isolation of > 120 dB (via a combination of cross-polarization isolation, spatial isolation, and nonlinear canceling).