The improvement of tri-plate line performance by using corrugated transitions

A novel structure is investigated for the improvement of tri-plate line (TPL) performance. Based on experience in the design of horn antennas, we introduce corrugations of the transition section of the TPL in order to achieve better field uniformity and to reduce the return loss. A corrugated transition waveguide may be viewed as the cascade of bifurcated metal waveguides. We employed the building-block approach, which breaks the overall structure into cascaded subcells, each of which may be analyzed rigorously by the mode-matching method. Thus, the input-output relation of each subcell is obtained as well as that of the overall structure. This enables us to carry out a parametric study on the field distribution inside the TPL test fixture, so that we can optimize its design for any required specifications.