JDS Uniphase CellAdvisor JD780A Series, User Manual

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JD780A Series Analyzers
Using Cable and Antenna Analyzer
491
Introduction
The Cable and Antenna Analyzer is a diagnostic tool needed to accurately detect operational problems
by performing cable and antenna measurements to verify the base
station’s infrastructure, including
feed lines, connectors, antennas, cables, jumpers, amplifiers, and filters. The JD785A Base Station
Analyzer and the JD786A RF Analyzer have all of the measurement functions necessary to verify
cable and antenna systems from Voltage Standing Wave Ratio (VSWR) to power measurements. In
addition, the JD785A and the JD786A make distance-to-fault measurements to pinpoint a faulty
location accurately.
To get maximum power into a load it is required that the load impedance match the generator
impedance. Any difference in impedance or mismatching would not produce maximum power transfer.
An impedance mismatch at the antenna system produces a reflective
‘traveling wave’, which goes in
the opposite direction from the incident wave. As the two traveling waves cross each other in opposite
direction, it is produce an interference pattern called a "standing wave". VSWR is the ratio between the
power sent forward to the cable and/or antenna and the amount of power that is reflected back to the
transmitter.
Some of the consequences of having a high VSWR condition in cellular services include dropped calls,
poor reception, and an overall unacceptable performance in the cell (or section of cell) covered by the
base station antenna. Therefore, the VSWR of the antenna system including the feed line is one of the
most critical factors in the service and maintenance of the RF transmitter systems.
This Cable and Antenna Analyzer function performs following measurements:
 Reflection: VSWR and Return Loss
 Distance to Fault (DTF): VSWR and Return Loss
 Reflection-DTF (dual measurement)
 2 Port Measurements: Vector and Scalar (Optional)
 Cable Loss (1 Port)

1 Port Phase
 Smith Chart
Display overview
Figure 245 provides descriptions for each segment of the measurement screen.