Planar Integrated Waveguide Diplexer for Low-Loss Millimeter-Wave Applications

Low-loss H-plane waveguide filters for planar integrated assemblies are described showing high attenuation near the pass-band due to a special modification of the outer inverter circuits. The outer irises are replaced by short-circuited T-junctions resulting in at least one pole above or below the pass-band. Such filters favorably can be combined to low-loss diplexer circuits for mm-wave applications. Examples of a single filter as well as of diplexers in the 28 GHz and 38 GHz frequency range are given.