FOCUSING OF ELECTROMAGNETIC-WAVES THROUGH A CONDUCTING SHEET INTO A LOSSY DIELECTRIC HALF-SPACE

The ability to focus electromagnetic fields into a lossy dielectric re gion is considered for the case where a thin highly conducting sheet i s located between the source aperture and the observer. An exact formu lation is presented for the aperture illumination which may be any fun ction of the horizontal (x, y) coordinates. The resulting expressions for the fields in the homogeneous dielectric region, above or below th e thin conductive sheet, are evaluated numerically for selected cases. In particular, it is shown that the presence of the sheet does not im pair the quality of the focus to any major extent, but the amplitude o f the field is diminished significantly. The double numerical integrat ion routines are validated by developing relatively simple asymptotic expressions for the fields which also can be employed as dependable fi eld predictors for regions not near the array.