Varactor-Tunable Frequency Selective Surface With an Appropriate Embedded Bias Network

In this work, a varactor-tunable frequency selective surface (FSS) is proposed; it is based on a common FSS composed of annular ring slot cells, in which four varactors are loaded on each annular ring slot to dynamically tune its resonant frequency in real time. In addition, an appropriate embedded bias network is added to introduce a same direct current bias voltage for each varactor. Numerical simulations demonstrate that the resonant-frequency of the proposed FSS can be tuned over a 77.2% wide frequency range from 2.73 to 6.16GHz by altering the capacitance of the varactors from 1.0 to 0.1pF; moreover, the embedded bias network has little effect on the band-pass response, and the minimum of the reflection coefficients is less than -24dB at all times. Finally, one effective experimental validation is carried out. The proposed tunable FSS possesses the merits of wide tuning range and high transmittance; thus, it has great potential applications in the design of tunable radomes or adaptive screening of unwanted wireless transmissions.