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Chapter 2 87
Making Complex Measurements
Making a Reflection Calibration Measurement
Converting Return Loss to VSWR
Return loss can be expressed as a voltage standing wave ratio (VSWR)
value using the following table or formula:
Where: RL is the measured return loss value.
VSWR is sometimes stated as a ratio. For example: 1.2:1 “one point two
to one” VSWR. The first number is the VSWR value taken from the
table or calculated using the formula. The second number is always 1.
Table 2-1 Power to VSWR Conversion
Return
Loss
(dB)
VSWR Return
Loss
(dB)
VSWR Return
Loss
(dB)
VSWR Return
Loss
(dB)
VSWR Return
Loss
(dB)
VSWR
4.0 4.42 14.0 1.50 18.0 1.29 28.0 1.08 38.0 1.03
6.0 3.01 14.2 1.48 18.5 1.27 28.5 1.08 38.5 1.02
8.0 2.32 14.4 1.47 19.0 1.25 29.0 1.07 39.0 1.02
10.0 1.92 14.6 1.46 19.5 1.24 29.5 1.07 39.5 1.02
10.5 1.85 14.8 1.44 20.0 1.22 30.0 1.07 40.0 1.02
11.0 1.78 15.0 1.43 20.5 1.21 30.5 1.06 40.5 1.02
11.2 1.76 15.2 1.42 21.0 1.20 31.0 1.06 41.0 1.02
11.4 1.74 15.4 1.41 21.5 1.18 31.5 1.05 41.5 1.02
11.6 1.71 15.6 1.40 22.0 1.17 32.0 1.05 42.0 1.02
11.8 1.69 15.8 1.39 22.5 1.16 32.5 1.05 42.5 1.02
12.0 1.67 16.0 1.38 23.0 1.15 33.0 1.05 43.0 1.01
12.2 1.65 16.2 1.37 23.5 1.14 33.5 1.04 43.5 1.01
12.4 1.63 16.4 1.36 24.0 1.13 34.0 1.04 44.0 1.01
12.6 1.61 16.6 1.35 24.5 1.13 34.5 1.04 44.5 1.01
12.8 1.59 16.8 1.34 25.0 1.12 35.0 1.04 45.0 1.01
13.0 1.58 17.0 1.33 25.5 1.11 35.5 1.03 45.5 1.01
13.2 1.56 17.2 1.32 26.0 1.11 36.0 1.03 46.0 1.01
13.4 1.54 17.4 1.31 26.5 1.10 36.5 1.03 46.5 1.01
13.6 1.53 17.6 1.30 27.0 1.09 37.0 1.03 47.0 1.01
13.8 1.51 17.8 1.30 27.5 1.09 37.5 1.03 47.5 1.01
VSWR
110
RL–
20
------ ----
+
110
RL–
20
-------- --
–
-----------------------=