Relationship between connector contact points and common-mode current on a coaxial transmission line

In this paper, we present the results from two independent experiments performed by adopting the Contact Failure Model, which provides an explanation of contact failures caused by faulty transmission line connectors, for the purpose of measuring the common-mode (CM) current, which is one of the factors causing noise radiation. The first experiment was carried out by gradually increasing the contact resistance, while in the second experiment the number of contact points was gradually decreased. Both experiments were performed within the uplink bandwidth of CATV Internet. From the results of these experiments, it was concluded that the relationship between the contact resistance and the CM current does not depend on the frequency. Furthermore, by analyzing the output from unit frequency within the uplink bandwidth of CATV, it was concluded that it is possible to predict the state of a faulty part causing contact failure. It was also shown that at least four contact points are necessary for the contact failure model in order to decrease noise radiation.