FSS Characteristics of a Coplanar Waveguide Left Handed Transmission Line on Ferrite Substrate

This paper presents the study of the performance of a left handed (LH) transmission line (TL) implemented using coplanar waveguide (CPW) over ferrite substrate longitudinally magnetic biased, magnetized in a direction parallel to the propagation direction, and periodically loaded with shunt planar strip inductors and series air gap capacitors. The dispersive negative permeability of the ferrite substrate allows the hosting CPW transmission line to exhibit tunable stobband propagation in addition to the conventional left handed propagation resulted from the left handed configuration. Therefore, the proposed transmission line represents novel frequency selective surface characteristics of multiple propagation bands with both left and right handed transmission. The tunable nature of the proposed line can be achieved by changing the applied magnetic bias. The proposed transmission line has the advantages of its low DC magnetic bias since it has very small demagnetization factor. The analytical analysis of the line has been studied and the simulated results indicate that multiple tunable propagation passbands can be obtained with transmission coefficient better than -3 dB with reflection level better than 15 dB over a moderate bandwidth.