Topband: Ground Conductivity

[Grant Saviers]

FYI some data which I found interesting

My dry earth at end of summer to very wet winter (WWA) causes my 
lightning ground system DC (actually about 300Hz AC) resistance to vary 
about 40% lower, ie 7+ ohms to 5 ohms.  There was also significant 
differences from rod to rod re resistance measurements.

How this affects RF properties is of course debatable but I do see a swr 
minimum shift of 10KHz or so on my T with 8 elevated radials.

One nearby expert (PhD ULF propagation) told me "acid rain washed out 
all the minerals here long ago.  We have poor ground."  If you really 
want to know the parameters, see antennasbyn6lf.com as Rudy describes 
techniques for ground RF properties measuring.

It is interesting to know the ground parameters, but what if you don't 
like them?  Gain and peak angle are affected, but for 1/4wl antennas - 
T, L, or full ht aren't significantly differentially affected.  For 
160m, put up the tallest you can with the most number of ground radials 
or 6+ elevated radials.  Much more on this on the N6LF web site.

For your flat open terrain place your yagis at heights for the arrival 
angles from geographies of interest to your QTH as shown in HFTA. 
Ground doesn't matter much.

Grant KZ1W

On 3/23/2020 15:57, Chortek, Robert L. wrote:
> Hi Dave,
> 
> I’m (just) starting to play with EZNEC and want to know what type of ground I’m dealing with when I’m running various models.
> 
> I live on the second fairway of a.golf course and the way it’s configured I have literally 1/2 to 1 1/2 miles of grass in certain directions.
> 
> It’s watered several times a week during the dry season and during the winter there is a fair bit of rain.
> 
> Don’t know what’s underneath.  It’s fertilized twice each year.
> 
> Thoughts on quality of the ground for 10-20 meters?  30-40 meters? 80/160?
> 
> Thanks!
> 
> Bob/AA6VB
> Robert L. Chortek
> 
>> On Mar 23, 2020, at 3:45 PM, Artek Manuals <Manuals at artekmanuals.com> wrote:
>>
>> [External Email]
>>
>> On 160M the " skin depth" of ground goes beyond the grass ...so it
>> depends on more than just your yard but also the type of soil
>> underneath, how often it is watered , fertilized etc etc.
>>
>> What are you trying to do that you need to know?
>>
>> Dave
>> NR1DX
>>
>>> On 3/23/2020 6:01 PM, Chortek, Robert L. wrote:
>>> A quick question for the collective wisdom on this esteemed reflector:
>>>
>>> How would one categorize the quality of ground consisting of grass.
>>> For example, if you live next to a large (many acres) open space made
>>> entirely of well watered grass, would that qualify as �average
>>> ground�, �above average ground� or something else?
>>>
>>> Haven�t been able to find the answer anywhere.
>>>
>>> Thanks for your input, as always!
>>>
>>> 73 es DX,
>>>
>>> Bob/AA6VB
>>> Robert L. Chortek
>>> _________________
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>>
>> --
>> Dave
>> Manuals at ArtekManuals.com
>> www.ArtekManuals.com
>>
>>
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