S820E Microwave Site Master™ User Guide : Measurement Review : Standard Line Sweep Measurements
 
Standard Line Sweep Measurements
To verify the performance of the transmission feed line system and to analyze typical problems, three types of line sweeps are required:
Return Loss
Cable Loss
Distance‑To‑Fault
The measurements for these sweeps are defined as
Return Loss — System Sweep
Cable Loss — Cable Loss Sweep
DTF — Load Sweep
 
Return Loss / VSWR Measurement
Return Loss measures the reflected power of the system in decibels (dB). This measurement can also be taken in the Standing Wave Ratio (SWR) mode, which is the ratio of voltage peaks to voltage valleys, as caused by reflections.
Cable Loss Measurement
Cable Loss measures the energy absorbed, or lost, by the transmission line in dB/meter or dB/ft. Different transmission lines have different losses, and the loss is both frequency‑specific and distance‑specific. The higher the frequency or longer the distance, the greater the loss.
Distance‑To‑Fault (DTF) Measurement
A DTF measurement reveals the precise fault location of components in the transmission line system. This test helps to identify specific problems in the system, such as connector transitions, jumpers, kinks in the cable, moisture intrusion, or mechanical damage.
Line Sweep Measurement Types
Return Loss – System Sweep
Return Loss is the measurement made when the antenna is connected at the end of the transmission line. This measurement provides an analysis of how the various components of the system are interacting. It provides an aggregate return loss of the entire system.
Distance To Fault – Load Sweep
A measurement is made with the antenna disconnected. The antenna is replaced with a 50 Ω precision load at the end of the transmission line. This measurement allows analysis of the various components of the transmission feed line system in the DTF mode.
Cable Loss – Cable Loss Sweep
A Cable Loss Sweep is a measurement made when a short is connected at the end of the transmission line. This condition allows analysis of the signal loss through the transmission line. This measurement identifies problems in the system. High insertion loss in the feed line or jumpers can contribute to poor system performance and loss of coverage.
This whole process of measurements and of testing the transmission line system is called Line Sweeping.
Advanced measurements are described in Advanced Measurements. They including Transmission (2‑Port), Transmission (External Sensor), Smith Chart, and 1‑Port Phase.