Spiral Antenna With a Circular HIS Reflector

This paper describes the antenna characteristics of a spiral antenna with a circular high-impedance surface (HIS) reflector (CirHISR). The CirHISR consists of a fan-shaped patch element array printed on the top surface of a circular dielectric substrate, and a perfect electric conducting reflector printed on the bottom surface of the circular dielectric substrate. The aspect ratio of each fan-shaped patch element, which is defined by the ratio of patch width to patch length, is approximately one. The axial ratio characteristics are analyzed using FEKO software based on the Method of Moment. Good axial ratio is obtained across a frequency range of 3 GHz to 10 GHz, where the antenna height is 0.9 cm (0.09 wavelengh at the lowest analysis frequency). In addition, other antenna characteristics, including VSWR, gain, and radiation efficiency are recognized.