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Re: [TowerTalk] Vertical and radials

To: towertalk <towertalk@contesting.com>
Subject: Re: [TowerTalk] Vertical and radials
From: Robert Harmon <k6uj@pacbell.net>
Date: Sat, 22 Jan 2022 10:27:52 -0800
List-post: <mailto:towertalk@contesting.com>
Thanks Jim


Bob
K6UJ




> On Jan 22, 2022, at 9:45 AM, Lux, Jim <jim@luxfamily.com> wrote:
> 
> On 1/22/22 9:21 AM, Robert Harmon wrote:
>> I love your perfect QTH description.   A hill of salt water, sloping gently 
>> in all directions.   hihihi
> Calistoga has hot water under pressure, and I'll bet it's got plenty of 
> dissolved minerals. So a big sprinkler fed from a hot spring at the top of 
> your hill.
>> 
>> 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 ?
> 
> millimhos per meter on the chart legend - that's milliSiemens/meter  in SI 
> units.
> 
> Yes, that's not exactly averaged over large areas, it's more "interpolated 
> from scattered measurements made in the 1930s and 1940s" for two purposes: LF 
> and MF propagation estimates and powerline grounding.
> 
> https://www.fcc.gov/media/radio/m3-ground-conductivity-map has a slightly 
> newer version, and also has some references to tabular data.
> 
> 
> 
>> 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.
> 
> There are some other datasets around, but they tend to be highly specific, 
> because someone had a need to measure it.  And there's not many needs.  
> Munitions depots, electrical installations, etc. are most likely, along with 
> some transmitter locations.  And there's no particular reason why those 
> measurements would be collected into a nice database, or even publicly 
> available.
> 
> You *might* be able to infer conductivity from a combination of geology and 
> soil moisture.  Soil Moisture *is* something for which there are datasets 
> from satellite measurements.  SMAP is a satellite specifically designed to do 
> that measurement, and it's measuring in L band.
> 
> 
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