Aluminum foil shield effectiveness for electronic cables

Historically, shielding of electronic cables has been expressed in terms of shield coverage. The numerical value used to delineate shield coverage corresponded to the actual area of the conductors covered by the cable shield. Generally, the larger the percentage of coverage the greater the shield's effectiveness. Presently, with the advent of more sensitive, more sophisticated equipment 100% shield coverage has not been totally adequate. Shield effectiveness can be defined as the functional capability of a shield. The shield must present any external signal from entering the conductors and also present the conductors from radiating signals beyond the shield. Both parameters of this function are important, but not necessarily proportional. This problem of proportionality occurs primarily in the type cable described herein.