Design of a Frequency-Tunable Frequency-Selective Surface with High-Selectivity

In this paper, a novel two-layered tunable Frequency-Selective Surface (FSS) with high-selectivity is presented. GaAs flip-chip varactors are also introduced in each unit-cell to achieve the frequency tunable capability and meanwhile maintaining lower insertion loss. At the meantime, four rectangular apertures are also etched on the ground to form the coupling aperture path, which results in the high selectivity. By changing the varactor capacitance from 0.12 to 1.0 pF, the center frequency of the pass band can be tuned from 2.36 to 5.46 GHz with a fractional bandwidth of 79.3% and with an insertion loss between 0.08 and 0.83 dB. This paper suggest that it is feasible to realize the capability of high-selectivity and frequency tunable simultaneously. This kind of highly-selective FSS is appropriate for radomes, spatial filters and frequency selective rasorbers.