Tx leakage cancellers for 24 GHz and 77 GHz vehicular radar applications

Tx leakage cancellers for 24 and 77 GHz vehicular radar systems are presented. These have high Tx-to-Rx isolation and wideband characteristics. Tx leakage cancellers are composed of four Lange couplers, a 90 degrees delay line, and a Wilkinson combiner. Tx leakage cancellers are implemented on GaAs substrate. A 24 GHz Tx leakage canceller shows the transmitting loss of 5.7 dB and Tx leakage cancellation of 28.1 dB. Also a 77 GHz Tx leakage canceller shows the transmitting loss of 3.6 dB and Tx leakage cancellation of 28.2 dB. Isolations due to Lange coupler are 15.1 dB in 24 GHz Tx leakage cancellers and 13.1 dB in 77 GHz Tx leakage cancellers, respectively. The isolations due to the topology of the Tx leakage canceller are expected to be 13 dB and 15.1 dB, respectively. These compact Tx leakage cancellers show wideband characteristics of bandwidth beyond 4 GHz.