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[KD0VE]

Getting ready to add a random wire antenna to my farm.  I have the table of preferred lengths and the feedpoint xfmr.  Various articles mention "getting it up as high as possible" but since at least some of it will be lower it would be useful to see the current distribution on the wire.

Looking for a link to a resource that would have charts of the current on a random wire.

thx to anyone taking the time to offer advice.

[W1VT]

Scroll down to see the current distributions on the wire for four bands.
https://www.qsl.net/kk4obi/EFHW%20Sloping.html

He has a download link to a 4NEC2 model that can be modified to your exact length and feedpoint location.

[KH6AQ]

The current distribution can be found using pen and paper. The current is zero at the far end. Working back from the end the current will peak at 1/4 wavelength, reach zero at 1/2 wavelength, peak again at 3/4 wavelength, reach zero again at 1 wavelength and so on.

Lwavelength = 492/F, where L is in feet and F is in MHz

Example:

Lwavelength = 492/14 = 35 ft.

[KD0VE]

thx. just what I needed.

[WB6BYU]

And here is an extended method of that technique
that works for many types of wire antennas.

[KE6SLS]

Tip my hat to you Dave.  Simple math, easy to understand.

73
j

[WA3SKN]

"Random wire"... far end is a high voltage/low current point.  Work backwards measuring in wavelengths or fractions of wavelengths to determine current locations.  This could also be measured using a snap ferrite meter and running along the wire.  Just think in terms of wavelength.  And height above ground matters.

-Mike.

[N0GV]

First, a "random" wire antenna is never truly random. We don't use a random number generator to get the length, we have design criteria like what will fit? and so on. Given that, a simple modelling program will give you the needed current distribution. MMANA, NEC etc. will work fine for that. They will also give you an idea of what your pattern will be.... Use them!

Grover