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 ex ample: 1.2:1 “one point two
to one” VSWR. The first number is the VSWR value taken from the
table or calculated using the for mu l a. 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
----------
+110RL–20
----------
–-----------------------=