Design and Implementation of Circular Polarized Patch Antenna Using EBG Structure

Modern wireless communication devices desire antennas with enhanced performance and low profile. EBG (Electromagnetic Band Gap) surfaces are artificially engineered to improve antenna performance. The performance of a square patch antenna over a 2D-Mushroom EBG ground plane is investigated by comparing patch antenna with conventional ground plane. In this paper, a circular polarized patch antenna resonating at 2.4 GHz, for ISM band applications is designed, fabricated and tested. The antenna is a square patch with truncated edges, exhibiting Right Hand Circular Polarization (RHCP). Circular polarization is crucial to eliminate antenna orientation requirements. Band gap nature of mushroom EBG unit cells are investigated and loaded between patch and the ground plane to eliminate back lobe and improve antenna performance. The mushroom EBG is designed to resonate at 2.45 GHz, with a forbidden band gap of 450 MHz, in-phase reflection band gap of 390 MHz and a high impedance of 3475 Ω at resonance. The introduction of EBG ground plane enhanced the gain to 5.35 dB with an excellent axial ratio at resonance and an operating bandwidth of 7%, with reduction in patch dimensions. The design was simulated in HFSS and tested using VNA after fabrication, resulting in highly correlated results.