Compact Notch Filters Using Vertically-Coupled Meander Stub Resonators

Abstract

In this paper, novel notch filters with compact size are proposed using two types (type I and type II) of vertically-coupled meander stub resonators. The new filter design methodology is derived from the concept of high impedance wire. This design methodology incorporates embedded meander λ/4 stub resonators. They are adopted as quasi-lumped-circuit elements for realizing compact size; vertical coupling is introduced to obtain a transmission zero. Lucid equivalent circuit models are given for both analysis and initial design. The center frequency, rejection bandwidth and level can be easily controlled by the stub parameters. To verify the design concept, two notch filters examples are designed and fabricated employing three cascaded types I and II stub resonators, respectively. Good insertion loss, sharp notch performance and compact size are achieved as demonstrated in both simulation and experiment.