Two-Path Cutoff-Waveguides for Filter Applications


IEICE TRANSACTIONS (1976-1990)   Vol.E73    No.5    pp.705-711
Publication Date: 1990/05/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Microwave and Millimeter Wave Technology

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This paper proposes a new type of evanescent-mode waveguide filters consisting of two parallel cutoff waveguide paths, in which a number of swelled portions are provided as resonators. One of two paths (the subsidiary path), mechanically connected to the main path in parallel, achieves the negative coupling to exhibit an elliptic-like feature. This type of filters includes a number of complicated waveguide-junction discontinuities. They are analized accurately by the full-wave analytical method based on the mode-matching method. After deriving the generalized equivalent network, the main-path structure is designed to exhibit the specified passband response by using its approximated network. The specified overall characteristic is then synthesized by a computer-aided design method by using an equivalent network without approximations. Measurements on the filters modeled in both X- and U-bands show excellent agreement with the designed characteristics, and prove the feasibility of two-path cutoff-waveguides for filter applications in the microwave and millimeter-wave regions.