Design of a Low Profile Broadband Spiral Antenna with a Cross-Slot UC-EBG Reflector

In this paper, design and realization of a Low Profile Archimedean Spiral Antenna is presented. The Low Profile Archimedean Spiral Antenna is printed on a substrate. The bidirectional radiation patterns of the antenna are converted to unidirectional using uniplanar EBG reflector. This uniplanar EBG ground plane is designed with modification in Compact Uniplanar Photonic Band Gap (UC-PBG) structure. The modified version of UC-PBG ground plane provides much wider bandwidth. This ground plane is tested for its electrical characteristics over the frequency band and used as a reflector with spiral antenna. An Archimedean Spiral antenna is designed and simulated in the frequency band of 0.5-6 GHz. The frequency band of operation for the EBG ground plane/ reflector is of the same order. The physical parameters of the antenna are studied for its electrical characteristics and these parameters are optimized for better electrical characteristics of the antenna. Antenna performance is also compared with conventional Metallic (PEC) reflector. The simulated results are validated with measurement. Comparisons of these results are presented. In this design, the height of the antenna is reduced by 86% compared to conventional cavity backed Spiral Antennas. The bandwidth of proposed EBG cell is 171.4%. For spiral antenna integrated with EBG reflector; the impedance and radiation patterns bandwidth are 169%, on axis axial bandwidth is 169% and off-axis axial ratio bandwidth is 163.6%.