Wideband and low-loss cavity filter using penta-mode resonator

In order to meet the demand of high communication capacity and high transmission efficiency in communication system, a construction of wideband and low-loss cavity filter is proposed. In this design, metal rectangular cavity is employed as the resonator, and five modes of this resonator are excited simultaneously by the feeding probe and perturbed metal posts. When adjusting the dimensions of the feeding probe and perturbed metal posts, the resonant frequencies of the multiple modes and transmission zeroes could be controlled. Accordingly, a wideband filtering response with high passband selectivity is formed. In the meanwhile, the high quality factor of the cavity contributes to the low insertion loss in the passband. After simulation and optimization in HFSS, the proposed filter is manufactured and measured. As the measured results presented, this design is centered at 11.2 GHz with the fractional bandwidth of 36%, the insertion loss is 0.25 dB, multiple transmission zeroes are close to the center frequency to enhance the passband selectively. The proposed penta-mode cavity filter possesses wideband, low loss and high passband selectivity, which is applicable to satellite and radar communication services.