Low-Cost Third-Harmonic Mixer for -Band Retrodirective System Applications

This letter presents a low-cost third-harmonic mixer suitable for${W}$-band retrodirective systems. Measured results show that when fixing the local oscillator (LO) frequency at 35 GHz, the conversion loss (CL) below 11 dB is achieved over the radio frequency (RF) range of 100–110 GHz with intermediate frequency (IF) from dc to 5 GHz, while for the RF range of 108 GHz, the minimum CL of 6.8 dB is obtained. Therefore, the presented mixer exhibits an excellent performance with low CL in comparison with that of a normal subharmonic mixer (SHM). The isolations of RF/LO and RF/IF are improved to the level of 35 and 38 dB, respectively. The simulated and measured isolations of LO/RF are 41 and 37 dB, respectively. This mixer has properties of low LO frequencies, high isolations, and low CL; therefore, it provides a high-performance and low-cost alternative solution for the applications of retrodirective systems.