A four-pole dual mode elliptic filter is realized in circular cavity without screws. The desired coupling and tuning actions are achieved by using a novel arrangement consisting in the insertion of a short section of inclined rectangular waveguide in the middle of the cavity body. In this way we realize dual-mode filters by using only junctions of waveguides with rectangular and circular cross sections, thus enabling a very efficient CAD of such filters. This arrangement also proves particularly convenient from the manufacturing viewpoint. Measured response of a breadboard channel filter operating at Ku-Band shows good agreement with theoretical simulations; a sensitivity analysis confirms the validity of the proposed design.

A four-pole dual mode elliptic filter realized in circular cavity without screws

A Ku-band, 3-channel contiguous multiplexer has been developed using 5-pole quazi-elliptic function filters. The channel filters are realized as a cascade of dual- and triple-mode cavities operating in the higher order TE/sub 113/ and TM/sub 012/ resonant modes. Measured data from the triplexer correlates well with theory.

A Ku-Band Contiguous Multiplexer Employing Low-Loss, Odd-Order, Mixed Dual-Triple Mode Cavity Filters

A novel type of circular cavity enabling two orthogonally polarised resonances to be coupled and tuned without using screws is presented. In order to achieve an accurate and efficient electromagnetic modeling, the coupling mechanism is realized by inserting in the middle of the circular cavity a short section of rectangular waveguide at an appropriate inclination angle. The proposed cavity allows one to realize dual-mode filters entirely by using junctions of waveguides with rectangular and circular cross-sections, thus enabling a very efficient CAD of such filters. Numerical analyses of this structure have been performed showing a noticeable agreement with measured data. It has also been confirmed, both theoretically and experimentally, the ability to achieve close control of resonant frequencies and coupling values without using screws.

A circular cavity structure for the efficient CAD of dual mode filters

Miniature, high performance asymmetric canonical filters utilizing dual-mode dielectric resonators are discussed. Filter synthesis is accomplished by proper rotations of the canonical coupling matrix. As an example, performace of realized 6-pole asymmetric canonical (6-4) and 8-pole self-equalized (8-4-2) filters are presented.

C. M. Kudsia

Papers

Manifestations and limits of dual-mode filter configurations for communications satellite multiplexers