Screening effectiveness of unscreened balanced pairs

Abstract

The screening effectiveness of screened balanced pairs is described by the transfer impedance ZT in the lower frequency range and by the screening attenuation aS and/or the coupling attenuation aC at higher frequencies. The screening effectiveness of unscreened balanced pairs can be measured in principle with the same test-set-up as for screened balanced pairs as near and far end coupling. It could be shown, that the screening effectiveness of a single unscreened balanced cable is equal to its unbalance attenuation whereas the screening effectiveness of multiple unscreened pairs, e.g. for data transmission is the sum of its unbalance and the screening effect of the remaining pairs not under test. At low frequencies, screening effectiveness of unscreened single and multiple balanced pairs can be described and measured as "Low frequency coupling attenuation".