Effects of Connecting Hardware and Terminals on the Screening, Crosstalk and Transmission Properties of an Over 100 MHz Datalink

Current copper based balanced data cables achieve extremely high symmetry and transmission performances. This factor together with the ever increasing frequencies, means that the so called connecting hardware (CHW), in spite of their short lengths of only a few centimetres, create the bottle neck for increasing the bandwidth of open data cablings into the hundreds of MHz. The studies presented in this paper show that CHW can no more be regarded electrically short and that special care must be taken immediately to improve its crosstalk performances by choosing a new mechanically symmetrical connecting interface structure, in which no systematic couplings are present. Additional care must be taken so as to ensure that the EM screening is sufficiently tight and reliable at joints, and that the characteristic impedances of CHW and cable do not differ by more than about 30 % of the corresponding return loss at high frequencies of about 17 dB.