A compact triband antipodal Vivaldi antenna with frequency selective surface inspired director for IoT/WLAN applications

Abstract

In this paper, an antipodal triband Vivaldi antenna operating in 2.4/5.2/5.8 GHz bands has been presented for WLAN/IoT applications. The proposed antipodal Vivaldi antenna has meander line shaped slotted lines, which are structured on the edges of exponentially tapered antipodal metallic branches and frequency selective surface (FSS) inspired director in the front part of the exponentially tapered patches on both top and bottom sides of the substrate. The meander line shaped slots on the tapered antipodal metallic branches have been utilized to improve the impedance bandwidth whereas FSS inspired director has RF performance effect on the enhancement of the gain and suppression of the side lobe levels in WLAN/IoT frequency bands. This FSS inspired director has the structural geometries in the form of meta-material based FSS consisting of an array of the sub-wavelength rectangular patches. These FSS structures are designed by global and local optimization processes using fast and efficient meta-heuristic algorithms, honey bee mating optimization (HBMO) and Differential Evolutionary. The optimized antenna model has been prototyped with the use of 3D printed substrate material based on PLA Filament-Polar White RBX-PLA-WH002 having predetermined filling form factor to obtain the desired substrate permittivity in the operating frequency bands. The simulated results of the proposed antenna design are in good agreement with the measured results. Furthermore the experimental results verify that the propotyped antipodal Vivaldi antenna has better RF performance as compared with the counterpart alternative designs in the literature. It can be concluded that the proposed antipodal Vivaldi antenna is a promising candidate for WLAN/IoT applications with high RF performance and easy integration into the microwave circuits.