A spiral antenna above a hybrid HIS-EBG reflector

This paper discusses antenna characteristics of a two-arm Archimedean spiral antenna above a hybrid HIS-EBG reflector. The hybrid reflector consists of an HIS and an EBG, where the HIS is located over an EBG reflector. The analysis is performed with a spiral antenna backed by a conducting plane (PEC) reflector and an HIS reflector, both with the equal total antenna height. It is shown that the HIS reflector contributes to improve the input impedance and axial ratio. Subsequently, antenna characteristics are analyzed for a spiral antenna above the hybrid HIS-EBG reflector. This revealed that the hybrid HIS-EBG is more effective configuration in improving the input impedance and axial ratio than the HIS configuration.