Abstract: A 0.17 THz Schottky varactors frequency doubler for 0.34 THz wireless communication system was presented in this paper, which can supply the low phase noise and low spurions of local oscillator (LO) signal. The doubler was based on quartz microstrip circuit integrated in waveguide cavity and with the Schottky varactor diodes constituting anti-parallel pairs as the key part. The modeling and simulation for the diodes were accomplished by combining the knot parameter model with three-dimensional electromagnetic model. Two ways were found to achieve a matching circuit for the optimal doubler design and a 0.17 THz doubler was fabricated and tested according to these simulating results. The test results indicate that, at the 80-86 GHz driving frequency and 20 dBm driving power, the maximum output power of the doubler is 12.21 mW with the efficiency up to 11% at 163 GHz, and it can reach to 21.41 mW while the input power at the saturation terminal.