[TowerTalk] 16om vertical and the number of radials

[Jeff Blaine]

At Dayton/Xenia antenna forum this year 2022, N9NB had a pretty 
interesting talk on low band verticals.  The key take-away from that was 
that you could reasonably determine your actual ground loss based on VNA 
measurement of your antenna, and comparing it with the model of same.  
Of course the caviets apply - the more simple and idealized your antenna 
is in reality, the easier it is to closely model the reality of the 
install and get a better set of ideal numbers to compare the measured 
against.

I had what I thought was a compromised set of 80m vertical grounds on my 
4SQ but after measuring it and comparing to my model, the result was a 
ground resistance of a few ohms - far better than I had expected.  So 
instead of fiddling with improving my ground system this year as 
anticipated, I decided to call CQ instead - and not worry about the 
fraction of a dB that I'm losing due to a less than ideal ground system.

73/jeff/ac0c

alpha-charlie-zero-charlie
www.ac0c.com


On 12/2/2022 12:29 PM, Jim Brown wrote:
> On 12/2/2022 8:22 AM, WESLEY ATTAWAY wrote:
>> I think you would have to look at the details re the really loud 
>> stations.  They probably do have good radial systems and also have 
>> particularly good ground/water/soil for fairly long distances around 
>> the antenna.
>
> YES! The earth is a big resistor. Soil quality affects transmitter 
> field strength two ways. First, loss in the soil very close to the 
> antenna make the antenna less efficient. Radials reduce this 
> component. Second, loss in the far field, distant from the antenna. 
> There's nothing we can do about this. There's an excellent discussion 
> of this in one of the ARRL publications, either the Antenna Book or 
> the ON4UN book.
>
> 73, Jim K9YC
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