Design Method for Wideband Direct-Coupled Resonator Filters with Electric or Magnetic Couplings (1144)

The paper presents methodology for designing wideband and ultra-wideband filters with electric or magnetic direct couplings based on closed-form formulas. For given filter specifications the method gives filter parameters as a set of resonant frequencies, coupling factors, external quality factors and characteristic impedance of the filter resonators. In this paper method for designing 5th order filters is described in details. High accuracy of the presented method is also addressed.