Electrically tunable miniaturized band-stop frequency selective surface on engineered substrate with embedded permalloy patterns

This paper presents a miniaturized and electrically tunable band-stop frequency selective surface (FSS) with magneto-dielectric engineered substrate which has high and electrically tunable effective permeability. The perspective magneto-dielectric substrate is implemented with multiple layers of 100 nm thick patterned Permalloy (Py) thin film embedded in Roger RT/Duriod 5880 substrate, and each Py thin film layer consists of an array of 15μm×20μm Py patterns with 10 μm gaps among them to suppress the magnetic loss. The tunability of effective permeability for the proposed substrate is achieved by the static magnetic field produced from the applied DC current through the patterned gold bias lines beneath Py patterns. The engineered substrate has been implemented and studied, results show that the substrate embedded with a single layer of patterned Py has an equivalent permeability of 1.14 with tunability of 3.3%, and the substrate embedded with ten layers of patterned Py has an increased equivalent permeability of 2.398 and tunability of 15.8%. A magnetic FSS is designed on the implemented engineered substrate to demonstrate the efficacy of miniaturization and tunability. Compared to non-magnetic FSS on normal dielectric substrate, the size of the designed FSS has been reduced by 16.02%, and the operating frequency of the proposed FSS is continuously tunable from 2.450GHz to 2.672GHz with DC current.