Created: 2026-04-26 16:37:12 - Touched: 2026-07-29 06:15:19 - Status: Seed

I've been licensed since 1996 and passed with the CW requirement. Currently holding Amateur Extra in the US and Basic with Honours in Canada.

Why is ham radio important to me? What are my history and goals here? How does this relate to other things in the garden?

Working

Learning

QSL (confirming contacts)

Antennae stuff

JPC-12/PAC-12

MagLoop

Other antenna stuff

Contesting

Bicycle setups

Community and disaster prep

Misc

SWR

SWR vs VSWR vs reflection coefficient. Constructive vs destructive interference. A SWR of 10:1 might be 5ohm or might be 500ohm at the point it connects to the radio, depending on the length of the feedline and the interference pattern.

VSWR is the voltage version of SWR. Reflection coefficient is the amount of voltage or power that's reflected back to the source when there's an impedance mismatch.

Reflection coefficient = Vreflected / Vforward

VSWR = (1+mag(reflection))/(1-mag(reflection))

The reflection coefficient then = (vswr-1)/(1+vswr)

Magnitude of reflection coefficient is the square root of the power reflected / power forward. Square the reflection coefficient to get power ratio: Pr/Pf = ((swr-1)/(1+swr))^2.

For 6 watts:

SWR Reflection Pr Pmin Pmax
1.0 0.00 0.00w 6.0w 6w
1.5 0.04 0.24w 4.0w 9w
2.0 0.11 0.60w 3.0w 12w
3.0 0.25 1.50w 2.0w 18w
4.0 0.36 2.16w 1.5w 24w

This means if your SWR is 4.0, your finals might be handling 1.5 watts or 24 watts for your configured 6 watts of output. That's a great way to overheat and damage your radio.

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