Equivalent circuits of microstrip discontinuities including radiation effects

An efficient theoretical method for the full-wave analysis of microstrip circuit elements has been developed, taking into account effects such as dispersion, coupling between elements, surface waves, ohmic and dielectric losses, and radiation. A de-embedding process allows the derivation of equivalent circuits independently of the feed model used. Results for bends and slots are in good agreement with measurements and reduce to quasistatic predictions in the low-frequency range. The method was first tested by analyzing a segment of a uniform microstrip line, and then it was applied to several two-port discontinuities (bends, slots, etc.). As shown in the theory, the method is easily extendable to any N-port structure. Discontinuities on other related substrate configurations (stripline, suspended, and multilayered microstrip) could be easily analyzed with this technique by using the pertinent Green´s functions.<>