摘要

This paper presents an ultra-miniature bandpass filter based on quarter-mode substrate integrated waveguide (QMSIW) cavity with negative-order resonance. Ramp-shaped slots are used as interdigital capacitors (IDCs) to force the structure to operate in the negative order resonance mode. A patch with triangular slots in an additional middle metal layer along with disconnected vias is also used to increase the equivalent series capacitance of the IDC and shifting down the -1st resonance for more miniaturization. The 2-pole filter has a center frequency of similar to 690 MHz with an area of similar to 0.05 lambda(0) x 0.09 lambda(0). The measured insertion loss is 2.1 dB and return loss is better than 30 dB. By employing the -1st order resonance, measured out-of-band rejection of >30 dB up to similar to 2.1 GHz is achieved. To the best of authors' knowledge, miniaturization factor of similar to 91% compared to a conventional 2-pole SIW filter shows this is the most compact SIW 2-pole filter reported in the literature.

  • 出版日期2015