Shielding Tests for Cables and Small Enclosures in the 1- to 10-GHz Range

Electromagnetic shielding tests in the 1- to 1O-GHz frequency range have been characterized by lack of repeatability and reliability. New test methods have been developed which correct most of the causes of erratic behavior and have been found to provide reasonably smooth curves when results are plotted against frequency. Study of the results obtained under various conditions of test indicates that the test procedures approach the desired goal of providing a measure of shielding effectiveness that is related only to the test item itself. The cable test procedures are usable with any type of shielded cable including multiple conductor cables with connectors not intended for RF usage. Cables may be tested in their final configuration without need for modification or removal of insulation, etc. Results are given for tests made under various conditions and are compared with results obtained previously with the triaxial test method. Evaluation of the test procedure for testing small shielded enclosures was performed by testing suitable boxes equipped with leakage openings that could be moved to various points on the surface of the box. The results indiate that the general effect on shielding of a particular type of opening remains much the same regardless of its location or orientation. Results are given for a number of opening designs under various conditions of test.