RF Cancellation of Coupled Transmit Signal and Noise in STAR across 1 GHz Bandwidth

The shrinking spectrum availability has led to the development of creative approaches for spectrum allocation and reuse. A most promising approach for spectrum is the simultaneous transmit and receive (STAR) scheme. A major challenge in realizing STAR is the coupling of high power transmit (Tx) signals into the co-located receiver, leading to strong signal interference in the operating frequency. In addition, to this direct interference, cancellation of harmonics and the transmit noise is also necessary. Overall, for successful STAR realization, 3 signal components must be suppressed, namely 1)Tx signal, 2)Tx signal harmonics, and 3)Tx noise. In this paper, we present the design of RF cancellation of these components across 1 GHz using antenna and filters. In addition, we also show the effect of Tx noise coupling in an array environment and means to suppress it.