Electrically Tunable Wideband Fabry-Perot Antenna Based on Thin-Film Ferroelectric Capacitor Structures

We developed a novel design of an electrically tunable wideband Fabry-Perot resonator antenna (FPRA). The antenna’s operating frequency band is 4.9–5.5 GHz, thereby it can be used in Wi-Fi terminals. To achieve a high gain value in the work frequency band, the tunable slot antenna loaded on thin film ferroelectric varactors was used as a feeding source. In the proposed antenna, varactors and control circuits were located on the bottom surface of the PCB plate in contrast to the existing designs. This minimized source antenna pattern distortion and increased total FPRA gain. Ferroelectric varactors were manufactured based on thin films of barium-strontium titanate in the paraelectric phase (with composition x=0.3). This material is attractive for use in microwave devices due to its high nonlinearity and low insertion losses. Ferroelectric varactors were produced, and their characteristics were measured. Obtained experimental data were used during the simulation of FPRA characteristics. Two-layer partially reflected surface was used to achieve a high gain value of the FPRA in the work frequency range. The simulation results showed that the proposed FPRA showed at least a 4 dB gain improvement in the frequency band of 4.9 to 5.5 GHz with a peak gain of 10.6 dB.