Analysis of Longitudinal Rectangular Waveguide Based Power Dividers/Combiners Using Multicavity Modeling Technique

Abstract

A complete method of moment (MOM) analysis of longitudinal rectangular waveguide power dividers/combiners using multi cavity modeling technique (MCMT) is the subject matter of this thesis. The technique replaces all the apertures and discontinuities of the rectangular waveguide based structures with equivalent magnetic current densities, so that the given structure can be analyzed using magnetic field integral equation (MFIE). The magnetic field scattered inside the cavity region due to magnetic current source is determined by using the cavity Green’s function of the electric vector potential. The cavity Green’s function has been derived by solving the Helmholtz equation for the electric vector potential for unit source. The scattered magnetic fields in the waveguide region due to the presence of the transverse magnetic current densities are solved by rigorous mode matching method. The main advantage of this technique is that it is possible to find the electric field across any given aperture, which is either parallel or perpendicular to the direction of propagation. This helps in extending the study to the power handling capability of the waveguide structure. Further longitudinal power dividers/combiners analyzed and designed in this thesis are compact in size and the output ports are in same plane which is an added advantage for phased array applications. Mainly, different kind of 1:2 and 1:3 power dividers and combiners are designed and analyzed in this thesis. In the longitudinal 1:2 power dividers/combiners family longitudinal E and H-plane power dividers/combiners, folded E and H-plane tee junction circuits are analyzed. E-plane junctions circuits are not matched to the junction so matching posts are inserted to the structure to get wide frequency response. Similar techniques are adapted to H-plane 1:3 power dividers and combiners’ cases. Crosstalk effect due to fabrication error has also been studied. Algorithms have been developed using MATLAB for determination of various quantities involved. Computed results obtained for the above waveguide power dividers and combiners have been verified by measured data with those of commercially available software simulated data.