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SWR (Standing Wave Ratio) affects the power output of your radio. The following table shows the effect of SWR for a
transmitter with 4 watts of transmitted power.
The formula: Power in Watts x ((SWR-1) x (SWR-1)) / ((SWR+1) x (SWR+1)) = Loss of Power in Watts
* ERP = Percentage of Effective Radiated Power
| SWR READING |
% OF LOSS |
ERP* |
WATTS AVAILABLE |
| 1.0:1 |
0.0% |
100.0% |
4.00 |
| 1.1:1 |
0.2% |
99.8% |
3.99 |
| 1.2:1 |
0.8% |
99.2% |
3.97 |
| 1.3:1 |
1.7% |
98.3% |
3.93 |
| 1.4:1 |
2.8% |
97.2% |
3.89 |
| 1.5:1 |
4.0% |
96.0% |
3.84 |
| 1.6:1 |
5.3% |
94.7% |
3.79 |
| 1.7:1 |
6.7% |
93.3% |
3.73 |
| 1.8:1 |
8.2% |
91.8% |
3.67 |
| 1.9:1 |
9.6% |
90.4% |
3.61 |
| 2.0:1 |
11.1% |
88.9% |
3.56 |
| 2.1:1 |
12.6% |
87.4% |
3.50 |
| 2.2:1 |
14.1% |
85.9% |
3.44 |
| 2.3:1 |
15.5% |
84.5% |
3.38 |
| 2.4:1 |
17.0% |
83.0% |
3.32 |
| 2.5:1 |
18.4% |
81.6% |
3.27 |
| 2.6:1 |
19.8% |
80.2% |
3.21 |
| 2.7:1 |
21.1% |
78.9% |
3.16 |
| 2.8:1 |
22.4% |
77.6% |
3.10 |
| 2.9:1 |
23.7% |
76.3% |
3.05 |
| 3.0:1 |
25.0% |
75.0% |
3.00 |
| 4.0:1 |
36.0% |
64.0% |
2.56 |
| 5.0:1 |
44.4% |
55.6% |
2.22 |
| 6.0:1 |
51.0% |
49.0% |
1.96 |
| 7.0:1 |
56.3% |
43.8% |
1.75 |
| 8.0:1 |
60.5% |
39.5% |
1.58 |
| 9.0:1 |
64.0% |
36.0% |
1.44 |
| 10.0:1 |
66.9% |
33.1% |
1.32 |
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