Shielding of an electric line source by a finite ground plane and a narrow metal strip

The article discusses the performance of a finite-width image plane in the shielding of an electric line source. The effect on the shielding effectiveness of a metallic substrate and superstrate laid under and above the line source and image plane is studied in detail. The results are obtained by solving the electric-field integral equation with the point matching method for the case of two-dimensional geometry. For the 30 cm-wide image plane used in the simulations, it is shown that over the 30-1000 MHz frequency band, a narrow strip can reduce the maximum radiated electric field by about 25 dB when the line source is centered over the image plane. Without the strip, the maximum radiated field can increase by up to 12 dB when the source is moved from the center to the edge of the image plane. A noteworthy effect obtained by the addition of the strip on top of the edge-positioned line source is a 14 dB reduction of the maximum radiated field. This fully compensates for the 12 dB increase obtained by moving the strip-less line source from the center to the edge of the image plane.