Topband: I need help proofing an Inverted L model I made please. 40’ x 143’, four 100’ radials, #14 wire.

[Artek Manuals]

Jim et all

I agree with what you say on all points when it comes to radials on the 
ground and salt water affects.

However I have always wondered about elevated radials . The NEC ( both 2 
and 4) models (not that those are to always be trusted) show very little 
(if any) improvement beyond four elevated radials, you have any theories 
on why that is? Intuitively (also not to be trusted) that is a lot of 
real estate in the spaces between

Dave
NR1DX

On 12/11/2020 4:37 AM, Jim Brown wrote:
> On 12/10/2020 11:14 PM, Raymond Benny wrote:
>> With said, I believe my ground absorption is very high so I feel the 
>> higher
>> numbers of radials helps greatly with my vertical efficiency and 
>> radiation.
>
> Hi Ray,
>
> The soil affects us in two important ways. First, poor soil burns 
> transmitter power underneath the antenna and it's near field. We use 
> radials to shield the soil from the field, and to supply a low 
> impedance path for return current. Magnetic fields produced around 
> each radial by virtue of current flow couples loss in the earth into 
> the radials in the form of series resistance. Loss in each radial is 1 
> squared R; each time we double the number of radials the current in 
> each is divided by two, so the power coupled to the earth by each 
> divides by four. So the more radials, the less power is coupled to the 
> earth. THAT'S why more is better. The result of all this is that loss 
> in the soil under the antenna reduces the total strength of our signal 
> by that amount.
>
> The second effect of soil is in the far field, where we field radiate 
> hits the earth and is reflected by it to form the vertical pattern. 
> The better the conductivity THERE, the our pattern will be both 
> stronger and at a lower angle. An antenna with its base just above sea 
> water is the extreme example of this -- the reflection is extremely 
> strong, and it is at a VERY low angle.
>
> We can help the first of these two effects with a good radial system, 
> but the only thing we can do about the second (the far field 
> reflection), is to move where there is better soil. Most of us live 
> where we do because we like living there for reasons other than radio. 
> And that includes me and my XYL.
>
> 73, Jim K9YC
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband 
> Reflector

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Dave Manuals at ArtekManuals.com www.ArtekManuals.com

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