ground conductivity in millisemiens/meter for the continental United States map

[BOOTY MONSTER]

Conductivity Map

i was reading this article about dipole vs. vertical 1/4 wave antenna and it links to the USA ground conductivity chart and figgured a few others may find it interesting .

http://www.eham.net/articles/10877

i was kinda suprised Virginia scored so low . i would have thought with all the lakes and ponds and rivers and our rich moist soil great for farming that we would have ranked near the top of the list . looks like the folks in eastern Texas and north of it have the best soil conditions for RF tx'ing with a little spot in California being at the top also .

according to the article even the very best soil conditions have only about %.5 (half of 1 %) of the efficency that saltwater has . if i recall correctly fresh water is way way down there too compared to salt water but better than the best soil conditions .

the article itself has some interesting comments about elevated ground radials too . but its my understanding that the frequency/band we talk on will change how RF behaves so im guessing the effects of soil conductivity will vary in the effect it has on our signals depending on what band were on .

anyhow , just thought id share it . and its a short read for those that (like me) can get lost in a whole bunch of technobabble .

 

[hookedon6]

i couldn't agree more with this statement: "Also, for those who pay homage to the SWR god, a lossy radial system actually gives a better match at the price of efficiency. "

some people just WON'T believe that the vswr can go up when a good radial field increaces the antenna efficiency.

 

[GLR]

15...I'll be damned

 

[hookedon6]

15...I'll be damned

just use a couple dump truck loads of rock salt

 

[Robb]

A multi-point ground rod linked with copper wire might amend this condition for those in poor ground conductivity locations. Just a thought.

I am in the part of CA that did well ("30"); that explains a few things.
Great find - and thread - BootyMon...

 

[Captain Kilowatt]

i couldn't agree more with this statement: "Also, for those who pay homage to the SWR god, a lossy radial system actually gives a better match at the price of efficiency. "

some people just WON'T believe that the vswr can go up when a good radial field increaces the antenna efficiency.

Exactly. The impedance of a 1/4 wave ground mount vertical over a perfect groundplane is about 35 ohms. A lot of hams will add radials until the SWR is 1:1 and then stop. The problem is that if they were to keep adding them the SWR would increase to 1.5:1 but the antenna efficiency would be MUCH better.

 

[Captain Kilowatt]

A multi-point ground rod linked with copper wire might amend this condition for those in poor ground conductivity locations. Just a thought.

Robb, all that's going to do for you is increase your lightning protection and do nothing for an RF ground plane. Poor ground conductivity areas need radials and the longer the better. Antenna efficiency and take off angle depends on ground conductivity out to several wavelengths when you add in the effects of the ground reflected wave as seen below.

 

[BOOTY MONSTER]

i agree cap'n kilo . this supports why i feel its so important to have an elevated groundplane at the feedpoint or bottom of our verticle omni antennas . heres another link i found helpful and ive posted befor about ground elements .

Antenna Notes

Antenna Notes

RF acts differently on different frequencies (from what i understand) so ill rely on the more technically savvy folks here to point out any comments that dont apply to the chicken band