A compact waveguide filtering structure with transmission zeros for multi-beam satellites

The paper presents a novel approach for realizing a compact filtering structure composed of single-mode low-loss rectangular waveguide cavities able to implement high-selectivity transfer functions of elliptic type. The creation of transmission zeros is obtained by disposing the cavities in a suitable geometrical configuration and exploiting the properties of the selected resonant mode (TE102). The proposed approach is employed in the design of a four-pole elliptic filter at Ka-band. This is the basic building block for the extension to a 6-pole filter with 2 transmission zeros that can be used in low-loss high-power and high-selectivity diplexers required by modern multibeam payload of last generation satellites operating at Ka-band and above.