A combined wave digital/full-wave electromagnetic approach used for response calculation in equivalent networks of microwave circuits

In this paper, a combined wave digital/full wave electromagnetic (EM) approach is used to synthesize wave digital networks of microstrip structures with step and capacitive gap discontinuities. The wave digital approach is applied to model uniform transmission lines in these structures, while the full-wave EM tool provides a generalized S-parameter description of discontinuities, used to generate their approximate equivalent network models. In the case of capacitive gap discontinuity in the end-coupled structures, the synthesis procedure is based on equivalent circuit representation by using admittance (J-) inverters and half-wavelength resonators. Wave digital model of J-inverter is formed by use of a two-port parallel adaptor. The combined technique is used for efficient modeling and analyzing of two different types of microstrip band-pass filters.