A New Class of Dual-Mode Microwave Filters for Space Application

A new class of direct-coupled cavity bandpass filters having the same number of equi-ripple attenuation-zeros as the order of the filter and an attenuation-pole on either side of passband is described. Filters are configured in dual-mode structure operating in the dominant or higher order modes. Synthesis is accomplished using optimization techniques. Experimental results for a sixth order filter at 12 GHz agree closely with the dicted response. The simplicity of structure and the sharp cutoff characteristics make this class of filters most promising for the multiplexing networks of communications satellites.