Elements of Frequency-Selective Surfaces with a Wide Tuning Range of the Resonance Frequency

Resumo

A method for extending the tuning range of the resonance frequency of the elements of bandstop frequency-selective surfaces (FSSs) by increasing the intrinsic capacitance of these elements, which are controlled by varactors, is proposed. The frequency dependences of the reflection and transmission coefficients for the FSSs with two types of elements (modified loops and modified dipoles) with an increased intrinsic capacitance are calculated. Prototypes of these elements controlled by Infineon BB857 varactors were fabricated, and the ranges of resonance frequency tuning were measured using the waveguide method. The maximum relative tuning ranges are 23 and 37% for modified loops and dipoles, respectively. These ranges are considerably wider than the ranges corresponding to common loops and dipoles..