Wideband bandpass filter with controllable bandwidth and high selectivity using two different types of resonators

Abstract

In this article, a new wideband bandpass filter (BPF) adopting two different types of resonators is proposed. The filter is constructed of four same open loop resonators and one inverted I‐shaped resonator located at the middle. As a result, compared with conventional BPF without inverted I‐shaped resonator, the proposed BPF exhibits one new transmission zero around the passband, which can adjust bandwidth and increase the selectivity at high‐side edge of the passband significantly. The desired bandwidth can be obtained where the bandwidth is basically proportional to the upper or bottom coupling gaps between inverted I‐shaped resonator and two adjoining open loop resonators. For verification, the proposed BPF is designed and fabricated where good agreement is observed. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1319–1323, 2015

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