If you have (or can borrow) one of the new nanovnas you can measure your
own soil conductivity:
https://duckduckgo.com/?t=ffab&q=measure+soil+conductivity+with+vna&atb=v98-1&ia=web
--
73,
-de John "Curly" NI0K in rural Debs, MN USA
Hamshack Hotline: 6100000271
https://www.qrz.com/db/NI0K
Robert Harmon wrote on 1/22/2022 11:39 AM:
Thanks Dave,
I will look into it.
Bob
K6UJ
On Jan 22, 2022, at 9:36 AM, Dave Sublette <k4to.dave@gmail.com> wrote:
Do you have an agriculture extension office or a Farm Services Admin office in
your area? You might try calling them and asking if they have that data. As
much grape growing as there is in your area, one would think that all of the
soil data is available.
73,
Dave, K4TO
On Sat, Jan 22, 2022 at 12:22 PM Robert Harmon <k6uj@pacbell.net
<mailto:k6uj@pacbell.net>> wrote:
I love your perfect QTH description. A hill of salt water, sloping gently in
all directions. hihihi
I am having trouble finding ground conductivity fro my area in the north San
Francisco Bay Area. Napa county.
Looks like my area shows a number 8. Where is he chart to find out what this
means in conductivity ?
Wish I could find a map that I could drill down closer to my QTH. I know it is
pretty good right now, we have had
lots of rain the last few weeks.
Bob
K6UJ
On Jan 22, 2022, at 3:58 AM, John Langdon <jlangdon1@austin.rr.com
<mailto:jlangdon1@austin.rr.com>> wrote:
The other thing that K5IU was clear about is that the ground under the
antenna is the dominant factor in performance regardless of the radials you
use.
If you have really low conductivity soil under the antenna, even if you
mount a vertical on a 1/4 wavelength radius copper disc, essentially an
infinite number of buried radials, you are going to get poor performance.
Elevated radials will be as good or better in that situation, and are less
work, but a high dipole, over poor soil, will be equal or better.
If you have really high conductivity soil, a modest number of buried radials
or a set of 4 1/8 wavelength elevated radials tuned with an inductor will
probably give you good performance.
If you are over salt water, a single resonant radial will work very well.
BTW the ground conductivity maps most of us have access to, like
https://commons.wikimedia.org/wiki/File:United_States_Effective_Ground_Condu
<https://commons.wikimedia.org/wiki/File:United_States_Effective_Ground_Condu>
ctivity_Map.png , are from data averaged over a large area and any given
location within an area on the map may vary widely from the average. The
perfect QTH is a hill of salt water, sloping gently in all directions.
73 John N5CQ
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