This paper presents a passive balanced tripler operating in the frequency range of 110-150 GHz. The tripler utilizes a circuit structure with two planar Schottky diodes in reverse parallel to improve input impedance characteristics. The balanced structure is achieved by manipulating the electromagnetic field modes of input and output signals, effectively suppressing even-order harmonics. By designing an input transition structure with filtering capability, the size is reduced, resulting in a compact, technologically simple, and wideband passive tripler. Joint simulations using HFSS and ADS indicate that with an input power of 200 mW, the tripler outputs around 7 mW near the center frequency, achieving a peak output efficiency of 3.5%. Over the frequency range of 110-150 GHz, the output power exceeds 2 mW.