DGP stripline resonator for wideband filter application

This paper presents the results of a stripline/triplate S-shaped resonator that has similar characteristics to a conventional microstrip ring resonator having resonant peaks at identical frequencies. A stripline/triplate ring resonator is analysed first to characterize its electrical performance on a given dielectric substrate. Then an S-shape resonator is proposed as an analogue to the conventional ring resonator, which exhibits a comparable transmission response with the advantage of being significantly smaller in size. The results show that the S-shape structures´ high loaded Q-factor of 300 is comparable in magnitude to a suspended stripline resonator. It is also demonstrated that the S-shaped resonator can be transformed into a novel wideband bandpass filter by defecting its ground-plane (DGP). This is accomplished with rectangular slots that are strategically located under the resonator. The resulting filter exhibits an excellent transmission and return-loss characteristics.