Compact antenna module with optimized Tx-to-Rx isolation for monostatic RFID

In this letter, a compact monostatic antenna module with Tx-to-Rx isolation optimized by on-board reconfigurable leakage canceller and balanced antenna structure is presented. The self-interference of monostatic structure is managed by a directional coupler with impedance mismatch (Γ) reflector integrated into the antenna module with small area occupation. Also, quadruple inverted-F antenna is adopted to minimize the effect of antenna load variation and reduce the overall module size. The proposed antenna-integrated module was implemented and tested at 917 MHz as a UHF radio-frequency identification application. The measurement with various tag antennas showed the improvements in Tx-to-Rx isolation characteristic more than 20 dB and tag read distances.