Electromagnetic scattering by finite periodic strip grating on a grounded dielectric slab

Electromagnetic radiation and coupling problems by the finite periodic strip grating geometry on a grounded dielectric slab are investigated from the viewpoints of both the leaky wave antenna and the grating coupler. It is shown that the present geometry gives almost the same radiation pattern as that of the finite periodic slot geometry in the parallel-plate waveguide (taken as the simplified problem of the finite leaky wave antenna of the rectangular waveguide with one sidewall replaced by an inductive grid grating) by comparing the radiation patterns of two geometries. It is also shown that the present geometry has the advantages of better impedance matching and higher radiation efficiency even for the smaller size as well as easy fabrication for the leaky wave radiator application for millimeter waves over the periodic notch geometry on a ground plane covered by a dielectric slab. Concerning the grating coupler application, the performance of the present geometry is observed to be comparable to those of the previous finite periodic notch geometry on a ground plane as well as grating couplers used in integrated optics. In conjunction with the method for improving the coupling efficiency in the grating coupler application, a the discussion on the method for improving the aperture efficiency of the travelling wave antennas of the leaky wave type is touched upon.