An Examination of the Shielding Provided by the Use of Cable Trays

The magnetostatic behavior of a magnetic field in a perfectly conducting trough is analyzed as a two-dimensional boundary value problem, and equations describing the attenuation of the field by the tray are presented. The feasibility of using an open tray to provide shielding for cables is then discussed. Comparisons between the response of a wire over a ground plane and the response of a wire partially in tray are made, indicating that extremely good grounding is required to obtain any shielding from the tray at high frequencies.