Thermally Tunable Frequency‐Selective Surface Based on VO₂ Thin Film

Abstract

An approach to a design of tunable frequency‐selective surfaces (FSSs) for radio frequency (RF) domain based on vanadium dioxide (VO2) thin films is proposed. As an example, a thermally tunable annular slot FSS with integrated VO2 switchable elements for C‐band of the RF domain is described. Switching is based on abrupt change of conductivity of the VO2 film, initiated by heating from room temperature to a temperature of the metal–insulator phase transition of 44 °C. A tuning mechanism of the FSS allows continuous change of frequency response from room temperature state, where the FSS acts as a band‐pass filter, to high‐temperature state, where the FSS works as a reflector. In the process of tuning, a reflection coefficient at a central frequency of the filter can be increased from −26.4 dB up to −2.2 dB. The proposed approach can be used for the design of tunable FSS for applications that allow thermal control of the frequency response.

Use of Thermochromic Properties of VO2 for Reconfigurable Frequency Selection

“…Several studies have employed VO 2 thin film for FSS and spatial filter applications in the THz region [47][48][49][50][51] and RF region [52][53][54]; however, these designs consist of metallic resonators and slots with switchable VO 2 layers limited to dual states. In this work, we present a dynamically reconfigurable FSS and spatial filter capable of operating at a wide range of frequencies and states, limited only to the number of unit cells that can fit onto the film surface.…”

Novel versatile topologies and design optimization of wide-bandstop frequency selective surfaces for X-band, Ku-band and millimeter-wave applications

“…The Fig. 1e shows the equivalent circuit model of the proposed FSS structure [56][57][58][59][60] . The unit cell contains an inductor and capacitor, which forms a parallel LC circuit.…”