Design of 915 MHz Low-Loss Through-type Harmonic Transponder

This paper presents a 915 MHz low-loss harmonic transponder for harmonic radar sensors. The proposed through-type harmonic transponder comprises an input and output matching network with an independent impedance control circuit. This control circuit enables the independent matching of the input and output loads. The circuit minimizes the impedance influence between the input and output matching networks, regardless of the impedance change of the input and output terminals according to the internal and external environments. The designed harmonic transponder was implemented and its performance was measured. The results show that the conversion gain of the proposed circuit is >−10 dB over a wide input power range of −20-0 dBm. Furthermore, the implemented circuit maintains the conversion gain of over −11.5 dB and the low fundamental output power of under −32.2 dBm in the frequency range of 900-930 MHz.