Microstrip antennas and arrays on photonic band gap substrates

Patch antennas have some limitations such as restricted band-width of operation, low gain and a potential decrease in radiation efficiency due to surface wave losses. In this paper, the ability of a photonic band gap (PBG) substrate to minimize the surface wave effects is analyzed for a thick and high ε_r substrate. Two different types of PBGs are used, one the conventional dielectric PBG and the other a metallodielectric PBG. The PBG patch antenna showed significantly reduced levels of surface modes compared to conventional patch antenna, thus improving the gain and far-field radiation pattern. The results also showed that introducing metallic cylinders in dielectric crystals is more effective in suppressing side lobe radiation. The performance improvement of a two-element array of patches on the PBG substrate is also analyzed.