Influence on unwanted dielectric slab modes generated in slit array planer antenna supported by copper-coated dielectric substrate at 60 GHz

A planar antenna fed by an oversized hollow metal waveguide, whose top plate consists of slit array etched on a copper-coated dielectric substrate, has been proposed at 60 GHz band. We tried to make a uniform aperture distribution on the slit array to improve the antenna efficiency. The gain was not however increased and the radiation pattern was degraded compared with that based on the Kirchhoff´s scalar approximate theory. To overcome such difficulty, we investigated unwanted slab modes generating in the dielectric substrates.