[TowerTalk] radial lengths ...

[W0MU Mike Fatchett]

I have read a number of places that radials that exceed the height of 
the antenna are not worth it.   From what I understand more of whatever 
length you have for on ground or buried radial is better.  If you have 
an L with a vertical section of 50ft, I would assume that you would not 
need radials longer than 50 ft?  I don't know if this can be modeled of 
if anyone has actually tested or tried it.

Also for insulated wire the length will be less because of the velocity 
factor or 1 to 2 percent.  Most of us do not have the luxury of clear 
space that allows room for full sized radials around the entire 
antenna.  Do what you can, divert them around objects if it makes sense.

Having a screen down close in can help if you are limited as the closer 
in field seems to have a great effect on the efficiency?  I am no expert 
but have been reading a bit.

Good luck!

W0MU


On 11/30/2016 11:23 AM, StellarCAT wrote:
> For the ‘experts’ out there ...
>
> So question.... in ON4UN’s book it is stated in abundance that one should use typically 0.25 wl radials... the length of course varies with the properties of the earth and the desired end results but somewhere around 32 1/4 wave radials seems to be within about 1 db of 100+ of the same length ...
>
> but he also states, kind of “on the side” in one sections only (it seems) due to the velocity factor attributed to the earth that 1/4 wave is actually physically only 0.14 waves in length!
>
> So which is it – when it is stated 32 1/4 wave is that physically 1/4 wave or is it physically say 1/7th wave (and still electrically 1/4 wave)?!
>
> so for example on a 160 meter vertical are we looking at 32 ~130’ radials or more like 75’ radials (with the end of each of those not having enough current in them to contribute appreciatively to the current distribution)... ?
>
> I know most will respond with 1/4 wave.... but I’d bet most would be going by the generic statements of “1/4 wave radials for verticals”... if indeed the VF makes going beyond about 1/6th wave of very little value (again talking about 32 radials here – not 120) ... then why go through the effort?
>
> if this is (more) clearly stated in John’s book please let me know where.
>
> Gary
> K9RX
>
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