Improved Antenna Gain and Efficiency Using Novel EBG Layer

Abstract

this paper discusses the feasibility of using Electromagnetic Band Gap (EBG) structures to enhance the gain and efficiency of conventional square microstrip patch antenna. A single layer of $3 \times3$ EBG array placed on a microstrip antenna with a height of 80 mm is proposed for WLAN applications. The EBG unit cell is inspired from asterisk shape and structured as square geometry with 8 pins.The performance of the proposed antenna with and without the EBG structure is reported to identify the gain and the aperture efficiency enhancements. The antenna is mounted on a low cost FR4 substrate with maximum dimensions of $85 \times 85 \times1.55mm^{3}$ with relative permittivity of 4.2 and a loss tangent of 0.02 backed with a full copper ground plane. The EBG structure is mounted on FR4 substrate of 0.55mm thickness. A coaxial feed is used to excite the microstrip patch antenna through SMA connecter. The antenna S11, bandwidth, aperture efficiency and boresight gain are investigated with and without the EBG structure. The EBG operation principles are discussed through simulations using CST MWS of Finite Integration Technique (FIT). The proposed EBG structure provides a remarkable enhancement in the bore-sight gain from 1.5 to 11.2 dBi at 5.8 GHz with an aperture efficiency increase from 4.1% to 38.8.