A Dispersive Coupling Structure for In-line Helical Resonator Filters with Transmission Zeros

In this paper, a dispersive coupling structure for helical resonator filters is proposed for generating transmission zeros (TZs) in an in-line coupling topology. The coupling structure is composed of two interleaved helical resonators with a connecting wire between two helically wound arms. A linear frequency dependence of the coupling value makes the synthesis and design of such a filter straightforward. It is found that both the intercept and...