Multi Conductor Hybrid-Mode Approach for the Design of MIC Couplers and Lumped Elements Including Loss, Dispersion and Parasitics

A hybrid-mode approach for the analysis and design of MIC (Microwave Integrated Circuit) interdigital couplers and lumped elements consisting of multistrip configurations is described. At high operating frequencies this approach means an improvement compared to the common quasi-static techniques since for the first time it takes into account rigorously the dynamic effects of dispersion, dielectric loss and conductor loss. It is based on a very efficient spectral-domain technique for the frequency-dependent characterization of multiple-coupled strip 2n-ports in a multilayer dielectric medium, with a number of strips up to n = 10 as a practical limit on microcomputers (n = 20 on minicomputers). Discontinuity parasitics and launching effects are considered using state-of-the-art models. The frequency-dependent characteristics of multiple-coupled strip configurations are discussed in detail. From this some general conclusions are drawn concerning the improvements in design accuracy for multistrip components. The validity of the approach is demonstrated for the case of an interdigital coupler and an interdigital capacitor.