Theory and experiment of novel microstrip slow-wave open-loop resonator filters

This paper presents the theory and experiment of a new class of microstrip slow-wave open-loop resonator filters, A comprehensive treatment of capacitively loaded transmission line resonator is described, which leads to the invention of microstrip slow-wave open-loop resonator, The utilization of microstrip slow-wave open-loop resonators allows various filter configurations including those of elliptic or quasi-elliptic function response to be realized, The filters are not only compact size due to the slow-wave effect, but also have a wider upper stopband resulting from the dispersion effect, These attractive features make the microstrip slow-wave open-loop resonator filters hold promise for mobile communications, superconducting and other applications, Two filter designs of this type are described in detail, The experimental results are demonstrated and discussed.