A New Trapezium FSS Superstrate for Antenna Gain Enhancement

In this paper, a new frequency selective surface (FSS) for antenna gain enhancement is proposed. The antenna and FSS have an isosceles trapezium geometry. Three different versions of an antenna are created. For each version, the S-parameters S11 and S21 were simulated with the software CST Microwave Studio®. Then, one of the three trapezoid antennas is simulated with an FSS. These two devices, antenna and FSS, were manufactured and had the S11 and S21 parameters measured at the laboratory. The resonance frequency obtained for the trapezium FSS was equal to 2.27 GHz for $\alpha$ equal to 0 °, 2.70 GHz for $\alpha$ equal to 15 ° and 3.12 GHz for $\alpha$ equal to 30 °. The simulated antenna gain increased when the FSS is used as superstrate. Without the presence of the FSS, a maximum gain of approximately 1.50 db occurs at 2.20 GHz, when using the FSS as superstrate, the gain increases to approximately 5.25 db. The measured results agree with the simulated results.