Topband: Measure dipole on ground to get VF of BOG.

[Don Kirk]

Hi Mikek,

Speed of Light = Frequency x Wavelength
Therefore: Speed of Light/Frequency = Wavelength
Speed of light = 299 792 458 m / s (I normally just use 300,000,000 m/s)
Therefore: (300,000,000m/s) / (1190000 Hz) = 252.10 meters  But this is a
full wavelength, so you have to divide 252.10 meters/2 = 126.05 meters to
calculate the length of a 1/2 wave dipole on 1190000 Hz.

But your dipole is not 126.05 meters long, it's 79.248 meters long.

Therefore Velocity Factor is 79.248m/126.05m = 0.629

Hope this helps.

73,
Don (wd8dsb)


On Sat, May 2, 2020 at 4:58 PM Mikek <amdx at knology.net> wrote:

> I laid down 260ft of wire as a dipole on the ground, it is resonant at
> 1190kHz.
> I calculate this as a VF of 0.685, my calculation is actually 0.315 but
> I don't think that's right,
> so I subtracted from 1. Can someone post the proper formula to calculate
> the VF using Resonant frequency and Length.
> 260ft = 79.248 Meters  Frequency is 1190kHz.
>
>                         Thanks, Mikek KF4ITA
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