A more accurate analysis and design of coaxial-to-rectangular waveguide end launcher

An electromagnetic model is developed for the analysis of the coaxial-to-rectangular waveguide transition of the end-launcher type. The model describes the coupling mechanism in terms of an excitation probe which is fed by a transmission line intermediate section. The model is compared with a coupling loop model. The two models have a few analytical steps in common, but expressions for the probe coupling model are easier to derive and compute. The two models are presented together with numerical examples and experimental verification. The superiority of the probe model is illustrated, and a design method yielding a maximum voltage standing wave ratio of 1.035 over 13% bandwidth is outlined