Slot split ring resonators and its applications in performance enhancement of microwave filter

In this paper, slot split ring resonator (SSRR) is proposed as a suitable component for performance enhancement of microwave filters. The close-form formula for calculation of the resonance frequency of SSRR is obtained from a detailed parametric study. Firstly, SSRR has been employed for enhancing bandwidth (BW) of band stop filters (BSFs). Using the same device area, we can achieve a stop BW of 3.5 GHz from the novel BSF using SSRR. Whereas conventional open stub BSF can achieve a stop BW of 1.36 GHz only. Using SSRR and spurline, the stop BW is enhanced 2.57 times the conventional BSF using the same device area. Secondly, SSRR has been used for harmonic suppression of lowpass filters. Spurious harmonic passbands at 2^nd, 3^rd, 4^th and 5^th harmonics have been completely suppressed well below 20 dB rejection level without visible changes in the passband filter characteristics. Many of the harmonic suppression techniques in the literature discuss about harmonic suppression up to 2^nd and 3^rd harmonics only. It has been verified both from the simulation as well as experimental results that SSRR is a viable candidate for the performance enhancement of microwave filters.