Shielding Effectiveness of Long Cables

In this paper, we discuss a revised triaxial method for testing the shielding effectiveness of long cables. Using this method, measurements show that the commonly accepted rule that doubling cable length decreases the shielding effectiveness by half (6db) holds only for a very special case. In general this rule is not even approximately true, and data are given to illustrate the point. Finally, reasons for the failure of the doubling law are briefly discussed.