Dual-mode circular waveguide filters without tuning screws

Abstract

The manufacture of dual-mode circular waveguide filters is a complex and labor-intensive task that could be greatly simplified with the use of accurate and fast CAD tools to predict the electrical behavior of the structures being developed. This is especially true for the tuning screws assembly that is an integral part of this type of filter. A method is proposed for the rigorous and efficient analysis of the tuning screws assembly for dual-mode filters in circular waveguides. The method is based on the introduction of a new waveguide called a ridged circular waveguide and in its use as a key component for the implementation of dual-mode filters. The modal spectrum of the ridged circular waveguide is investigated using the finite-element technique to show how the introduction of this waveguide can effectively resolve the problem of the CAD of the tuning screws in dual-mode filters in circular waveguides.