FULL-WAVE MODELING OF CONDUCTING POSTS IN RECTANGULAR WAVE-GUIDES ANDITS APPLICATIONS TO SLOT-COUPLED COMBLINE FILTERS

A full wave model of conducting posts in rectangular waveguides yieldi ng their generalized S-matrix is presented. By cascading the generaliz ed scattering matrices of the posts and waveguide discontinuities, slo t couplings between two combline resonators are obtained. The validati on and accuracy of the method are confirmed by comparing the numerical results with measured data, It is shown that both electric and magnet ic couplings can be obtained by changing the slot positions, and the e lectric coupling is more sensitive to the tuning screw than magnetic c oupling. A 6-pole slot coupled combline filter,vith asymmetrical trans mission zeros is designed and built. Excellent filter responses are ob tained.