Radiation Characteristics of Antenna with External High-Impedance-Plane Shield

Kazuoki MATSUGATANI  Makoto TANAKA  Toshiya SAITO  

IEICE TRANSACTIONS on Electronics   Vol.E86-C   No.8   pp.1542-1549
Publication Date: 2003/08/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Microwave and Millimeter Wave Technology)
antenna,  high-impedance surface,  microwave,  

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The new hybrid antenna structures having external high-impedance-plane (HIP) shield are proposed. These antennas consist of normal patch or dipole antenna, working as a radiator, and HIP shield working as a reflector. The external HIP shield helps to reduce the undesired backward radiation. Generally, metal shield should be placed a quarter wavelengths apart from the antenna, but HIP shield can be placed close to the antenna and low profile structure can be obtained. In addition, compared with single-layer HIP antennas, having a patch surrounded by HIP structure, these hybrid antennas have the advantage of installation because the shielding effect can be obtained by attaching the external shield under the existing antenna. We fabricated HIP boards and combined with a microstrip patch or a regular dipole. The hybrid patch antenna with HIP shield improves the front-to-back radiation ratio (F/B ratio) similar to the single-layer HIP antenna or the hybrid patch with metal shield. But the dipole antenna with HIP shield, the F/B ratio is worse than the dipole with metal shield. These results indicate the TM mode antenna is suitable for the HIP shield in terms of the F/B ratio improvement.