A Low-Profile Equiangular Spiral Antenna Using a Novel EBG Ground Plane

In this paper, we adopt a novel electromagnetic band-gap (EBG) ground plane to reduce the profile of planar equiangular spiral antenna. The novel EBG structure is notched on every unit cell to form a square loop, combining the virtue of mushroom-like structure and tunable structure, which is not found in the correlative literatures. The lower resonant frequency means reducing the size of EBG cell in the same band-gap frequency. The novel EBG structure can emulate well a perfect magnetic conductor (PMC). The combination of EBG and equiangular spiral antenna produces a low-profile, high gain and wide-band antenna.