Compact, Tunable and Narrowband Waveguide Filters Using TM Dual-Mode Cavities for Satellite Communication Applications

A compact, tunable and narrowband filter using dual TM mode is presented in Ku-band as a channelizing filter in IMUX of satellite transponders. To shrunken the filter structure while keeping the resonator Q a pair of degenerated modes (TM120, TM210) are exploited. Consequently, a single cavity capable of providing two transmission zeroes besides two poles is achieved. Later, design steps of a four-cavity filter at central frequency of 10.97 GHz with 36 MHz bandwidth are reported and also compared with the experimental results. To improve the passband flatness, chamfered corners with tuning screws are used in the second version of the fabricated filter. The results satisfy the design requirements. The agreement between full wave simulation and the experimental results demonstrates the effectiveness of the proposed design approach.