An Overview of Problems Associated With the Design of Electromagnetic Shields

A significant number of papers have been written with regard to the shielding of electromagnetic waves. These papers typically start with a simplified overview of the propogation of electromagnetic waves from a dipole antenna and then launch into a detailed mathe­ matical treatise associated with a specific problem related to shielding. More often than not, the problem is one of obtaining a specific level of shielding given specific barrier materials and/or configuration. The paper will outline the basic problem, de­ velops the mathematical model used to predict the shielding and then verifies the results with test data. The necessity of verifying the test results dictates that the assump­ tions used in the mathematical model can be reproduced exactly in the test configuration. This, in turn, necessitates the use of well definable mathematical models simulating the test configurations. The basic mathematical models used by industry to predict the level of shielding of a given barrier emulates the assumptions used by the authors presenting the papers on shielding. That is, they deal with radiated fields propogated from radiators in which the properties of the wave are known, and the shield is of a homogeneous material that can be considered infinite in size with regard to the specific design under consideration.