Miniature ridge-waveguide filter module employing moldable dielectric material

The experimental 6-8.6-GHz five-pole bandpass filter being presented is composed of ridge-waveguide resonator segments, evanescent-mode inter-resonator coupling sections, and planar-circuit impedance-matching port networks. To reduce overall filter size, cavities are filled with a low-loss moldable dielectric material that does not shrink during curing. Good agreement is observed between measured and predicted filter response characteristics. Two additional bandpass filter designs with different fractional bandwidths further highlight the versatility of the design methodology that relies entirely on the use of commercially available general-purpose design software.