Tower mounted transmission lines are exposed to weather, and will degrade over time.Lightning can sever a portion of the antenna or damage the in-line lightning arrestor.The attenuation per foot or meter for the cable is also required in order to compensate for the attenuation versus distance.
Poorly tightened connectors and poor environmental seals are exacerbated by acid rain corrosion.
FDR is a transmission line fault isolation method which precisely identifies signal path degradation for coax and waveguide transmission lines.
Although the acronyms are similar, FDR technology is different from traditional Time Domain Reflectometry (TDR) techniques.
This dual role of predicting future failure conditions and isolating existing problems makes DTF an important part of service and maintenance on transmission lines.
DTF displays RF return loss or VSWR data versus distance.
A TDR cannot detect small performance changes at RF frequencies, so it is not possible to monitor performance degradation between maintenance intervals with these traditional methods.