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4.
4.1
To get maximum power into a load it is required that the load impedance
match
the
generator
mismatching would not produce maximum power transfer. A 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 produces an interference pattern called
a "standing wave". VSWR is the ratio between the power that is sent
forward to the antenna and the amount of the power that is reflected back
toward the transmitter.
Some of the consequences of having a high VSWR condition in cellular
services are: 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.
4.1.1
VSWR Display Description
The screen shown in Figure 4.1 is displayed when VSWR measurement
mode is selected. Various kinds of information related to the VSWR
measurement are shown on the screen.
VSWR
impedance.
Any
impedance
difference,
or
71
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