Topband: Ground mounted 1/2 and 1/4 wave verticals (was GAP)

[DAVID CUTHBERT]

Tim,

I believe those are valid conclusions. Referencing *Vertical antenna ground
system experiment #1*, by Rudy Severns:

1) Table 1 shows that going from 8 radials to 64 radials increases field
strength by* 1.6 dB*.
2) Figure 4 shows the resistive part of the base impedance changing from 58
ohms to 43 ohms.
3) Using a radiation resistance of 36 ohms the radiation efficiency for 8
radials is 62% and for 64 radials it is 84%. The difference is *1.3 dB*.

Rudy's other papers confirm the correlation between the resistive part of
base impedance and field strength.

    Dave WX7G

On Mon, Dec 17, 2012 at 4:21 PM, Shoppa, Tim <tshoppa at wmata.com> wrote:

> Dave... would it be a fair extrapolation to take your last sentence, and
> draw the conclusion that if adding radials changes feed impedance, then
> there was actual ground loss in the near field? Or that if we add more
> radials and feed impedance change is not seen, then we are at a minimum for
> ground loss?
>
> The above statements certainly align with my gut feeling, but my gut
> feeling is different than a mathematical proof :-)
>
> Tim N3QE
>