MIC bandfilters using open-ring resonators

The present work discusses the use of a half-wave open-ring resonator in order to ensure minimum surface wave excitation in MIC bandfilters. Comparison of open-ring filters with straightline filters shows that the open-ring filter has hardly any parasitic coupling, has no packaging problems, offers possibilities for nonadjacent resonator coupling resulting in high skirt selectivity, and has less insertion loss, especially for narrowband filters.