Topband: Accuracy of modeling of 160m verticals

donovanf at donovanf at
Tue Nov 6 16:01:05 EST 2018

Hi Ignacy, 

Salt water is very special! In a salt water environment potentially 
the entire Fresnel zone -- where as much a 6 dB of gain is obtained 
from ground reflection -- is in a highly conductive environment. 

Low angle radiation from a vertical with a salt water Fresnel Zone 
is much better than from an inland vertical. 

In a inland location only a very small fraction of the Fresnel Zone is 
covered by conductive radials. 


----- Original Message -----

From: "Ignacy Misztal" <no9e at> 
To: topband at 
Sent: Tuesday, November 6, 2018 8:45:28 PM 
Subject: Topband: Accuracy of modeling of 160m verticals 

A number of articles analyzed 160m verticals by simulation. Once the height 
was lambda/8 and the number of radials >= 16 (buried) or >=4 (elevated), 
the difference in gain was at most a few db. 

I operated the 2017 Stew contest from a northern beach of St George Island, 
FL. The antenna was inv L about 55 ft vertical and 90 ft horizontal,. with 
one 70ft radial elevated 5 ft. 

The performance was astounding. EU was heard one hr before the sunset, in 
bright sun..During the contest, EU were only slightly weaker than the US. A 
special point was easily working a DL with 100W while a well known 
contester using high power 100 miles inland could not work it. 

So it seemed that the salt-water enhancement was like 15 db, not a few. I 
wonder whether simulations are inaccurate with respect to radials/soil 
type or is salt water special? 

Ignacy, NO9E 
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