Compact Intermodulation Modulator for Phase Reference in Passive Intermodulation Measurements

In this article, a modular designed intermodulation (IM) modulator based on coherent nonlinearity superposition is demonstrated. A coherent combination network for two nonlinear sources (diodes) is composed, excited by a set of two-tone carriers, and the IM products generated from two diodes are inherently coherent. The designed IM phase and magnitude are synthesized by using two IM signals with different magnitudes. The modulator is achieved by modular design, and the manufacture is simplified by using low IM laminate and normal FR-4 substrate to the section with different IM sensitive levels. The work proves a solution to generate an IM phase and magnitude tunable reference for IM measurement, which also proves that IM can be used to carry some information.