Low-profile spiral antenna with a fan-shaped HIS/EBG reflector radiating a circularly polarized wave

This paper discusses the antenna characteristics of a low-profile spiral antenna with a fan-shaped HIS/EBG reflector. The antenna radiates a circularly polarized (CP) wave. The analysis is performed using method of moment. First, antenna characteristics are demonstrated with both a spiral antenna located in free space, and also one backed by a PEC reflector. It is shown that the axial ratio (AR) deteriorates when using a PEC reflector. Next, AR characteristics are analyzed for a spiral antenna with a fan-shaped EBG reflector. Here, it is shown that the AR is mitigated in comparison to that of the PEC backing spiral. However, CP wave is not obtained over a wide frequency range. Finally, antenna characteristics are analyzed replacing the fan-shaped EBG reflector with a fan-shaped HIS/EBG reflector. It is revealed that axial ratio less than 3 dB is obtained with a wide frequency range.