Using high impedance ground plane for radiation improving in microwave antennas

High impedance surface (HIS) is a kind of resonance-type microwave photonic crystals. In this paper, the HIS is used for a circular waveguide antenna, a dielectric rod antenna and a waveguide-fed slot antenna as high-impedance ground plane (HIGP). The HIGP has a very obvious surface wave bandgap. Suppression or reduction of surface waves is expected to improve antennas efficiency, and to bring a reduction of back lobe level due to diffraction of surface waves. The measured radiation patterns show that an addition in the antennas gain and a distinct reduction in the back lobes if the antennas work frequency are in the HIGP surface wave bandgap.