Bird Technologies AT-500-Manual - Manual (Page 39)

Measure Match
21
Match Efficiency (%)
Match Efficiency (%) indicates how much of the trans-
mitted power is being used and how much is wasted. If
the antenna system is perfectly matched, the Match
Efficiency would be 100%.
Return Loss (dB)
Return Loss (dB) is a comparison of the reflected sig-
nal to the forward signal in decibels. If the antenna
system is perfectly matched, the Return Loss would be
negative infinity dB.
Antenna manufacturers often use VSWR for specifica-
tions. Match Efficiency is popular for testing because it
is easy to determine a good match versus a bad match.
For example a system with a VSWR of 1.50 would show
-13.98 dB Return Loss and 96% Match Efficiency.
Auto Scale vs. Manual Scale
In swept mode Auto Scaling sets the measurement unit
scale to make the trace easier to read. However, if you
plan to look at the size or shape of traces for quick com-
parisons, it might be more meaningful to set a standard
scale. Remember that it is possible to set the scale man-
ually so the information is not on the display at all.
Figure 7 Auto Scaling Swept Frequency Mode
Swept
Freq Single
Freq Util Test
VSWR
1.5
1.2
2.00 MHz 136.00
*
1.35
69.00 MHz
Field
Str