Old Tip Of The Week 6

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Uderstanding SWR(Standing Wave Ratio)
In theory, your transceiver has 50 ohm output and your antenna is 50 ohms.
If a 50 ohm cable (such as RG58/U, RG8X or RG8/U) is used,
all the power from your transceiver will be transmitted via the coaxial cable
and radiated by the antenna.
Under these conditions,
the SWR(Standing Wave Radio) of your antenna system would be 1:1.
In practice, the antenna must be 50 ohms, and tuned to the exact channel.
This condition seldom exists and standing wave are set up on the cable.
This SWR rob you of power and likewise range.
While 1:1 is not always possible to attain,
you should tune your antenna system so the SWR does not exceed 1:5 to 1,
or at maximum 2:1. Here some examples of the power losses for various SWR ratios:

SWR = Power Losses.

1:1 = 0%
1.3:1 = 2%
1.5:1 = 3%
1.7:1 = 6%
2:1 = 11%
3:1 = 25%
4:1 = 38%
Tip of the week by Russ Prince.

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