Theoretical and Experimental Studies of Inductive Grids

We present a rigorous theory for the diffraction by inductive grids, having circular apertures placed in doubly-periodic fashion in a thick, perfectly-conducting screen. We compare the theory with measurements made at millimetric wavelengths, both for normal incidence and off-axis (in the region of strong polarization effects). We discuss the conclusions to be drawn from the calculations and measurements on the use of such grids as low-pass filters, particularly in relation to their possible application in the field of solar energy.