A novel filter based on a dual-mode air-filled substrate integrated waveguide cavity resonator

This paper presents a novel filter based on an air-filled substrate integrated waveguide (SIW) cavity resonator. This structure is inspired by the air-filled SIW, recently proposed to realize integrated interconnects with reduces losses. The proposed resonant cavity allows introducing two poles and two transmission zeros in the frequency response of the filter. The size and position of the air-filled portion of the SIW cavity permits to control the resonance frequency of the first two cavity modes, thus setting the pass-band of the filter. The position of the input/output port allows controlling the position of the transmission zero. A filter operating at 4 GHz, with a relative bandwidth of 1.5% and two transmission zeros, has been designed and experimentally verified.