End-Fed Half-Wave

Length of wanted wire: \[ meters = \frac{300}{frequency in mhz} \]

Eg for 80m: \[ \frac{300}{3.5600} = 84.270 \]

Cut in half for the EFHW: 42.135 meters.

It will resonate on all harmonics: 7.100, 14.200, 28.400

Pair harmonics:

• 2, 4, 6, 8

Impair harmonics:

• 3, 5, 7, 9

To calculate frequencies just multiplicate the original frequency by the harmonic number.