Analysis and Synthesis of Millimetric E-Plane Diplexers in Rectangular Waveguide

A novel E-plane diplexer is proposed and discussed. Its feature is the matching section of the three-port junction, obtained by means of an E-plane septum, realized on the same mask as the branching filters and placed in the cavity of an abrupt E-plane junction. The latter is designed in such a way that, when combined with two, reasonably good filters, separately designed and suitably positioned, the resulting diplexer gives good performances without further optimization. This design technique, based on the properties of the scattering parameters of a reciprocal lossless three-port junction, is, as such, of general validity and easily extended to other structures.