Accurate Excitation of Waveguides Using Discrete Ports Together With TRL Calibration

A new method for the enhancement of the accuracy of the calculation of the scattering parameters of microwave devices is presented if discrete ports are used for the excitation of the structure to be investigated. It is shown how the inaccuracies of the simulation results inherent to the use of such discrete ports can be avoided by the additional application of the TRL calibration technique. This method, which is well-known in the high-frequency measurement realm, is briefly revised. The applicability of the proposed method is demonstrated for microwave structures with shielded as well as open waveguide terminals. Two examples are discussed in detail, namely, the excitation of a shielded structure with coaxial waveguide terminals and that of an open structure with microstip line terminals using appropriate discrete ports, respectively. Simulation results are given and their accuracy is assessed by comparing them to a corresponding waveguide port excitation.