Compact metamaterial unit-cell based on stepped-impedance resonator technique and its application to miniaturize substrate integrated waveguide filter and diplexer

Abstract

In this article, a new miniaturized metamaterial unit-cell using stepped-impedance resonator technique is proposed. The proposed unit-cell is used to miniaturize the physical size of the conventional complementary split-ring resonators (CSRRs). In the proposed unit-cell which is called complementary G-shaped resonator (CGR), the slot line in the conventional circular CSRR is replaced with the stepped-impedance slot line. As well as, by carving two trapezoidal shapes inside the inner ring, the resonance frequency of the proposed CGR unit-cell has been more decreased. Compared to the conventional circular CSRR structure, the electrical size of the proposed CGR is decreased and miniaturization is occurred. To investigate the performance of the proposed CGR unit-cell in the size reduction, two substrate integrated waveguide filters and a diplexer are designed. To validate the proposed miniaturization technique, the designed filters and diplexer loaded by the CGR unit-cell are fabricated and measured. The measured results are in a good agreement with the simulated ones. The results shows that, a miniaturization factor about 0.69 is achieved.