High frequency and power source is most important for terahtz technology, and multipliers is common electronic way. This quadrupler design is only one stage to avoid impedance mismatches between multipliers. A proposed Schottky diode model improves the accuracy of design, which has considered the behaviors of current voltage (I/V), capacitance voltage (C/V), plasma resonance, and skin effect. Theoretical analysis was carried out by using harmonic balance simulations programs and three-dimensional finite element simulation tools to find the optimum embedding impedance for a given diode. Compact Suspended Microstrip Resonators (CSMRs) minimize the length/width ratio and make short idlers at the 2nd and 3rd harmonics. The experiment shows: the quadupler works at 325~351 GHz and output power is above 1mW between 334 GHz and 346 GHz, and the highest efficiency is above 3% with input power of 100 mW.