METHOD OF EXTRACTING THE EQUIVALENT CIRCUIT OF COMPLEMENTARY SPLIT RING RESONATOR LOADED TRANSMISSION LINE RELYING ON NEGATIVE PERMITTIVITY CHARACTERISTIC

In this work, a new approach for extracting electrical parameters of the equivalent circuit of complementary split ring resonators (CSRRs) loaded transmission line, based on the frequency band where negative electrical permittivity occurs, is proposed. For this reason, CSRR coupled to microstrip transmission line has been proposed and the behavior of the frequency band where negative permittivity appears is investigated, in order to specify the fundamental frequencies that are needed to calculate the electrical parameters of equivalent circuit. The procedure provides the electrical characteristics of CSRR (inductance, Lc, capacitance, Cc and intrinsic resonant frequencies). The obtained equivalent circuit model of CSRR loaded transmission line has been simulated and a good agreement is achieved between the results derived from the simulation and the ones form the equivalent circuit model. Further validity of the usage circuit is confirmed by applying different lengths of transmission line (host line); in this case, the frequency interval of negative permittivity band decreases and shifts to lower frequencies due to change in host line capacitance per unit cell. Nevertheless, the results of minimum insertion loss which were determined by the provided equivalent circuit model (which are proposed by the approach) are remaining compatible with the simulation. Ansoft HFSS (High Frequency Structure Simulator) simulator and Matlab are used for structures' design and analyzing the results.