[Fourlanders] RF and water

[Jim Worsham]

In general the lower the frequency the greater the depth of penetration BUT
there are a lot of conditions to that such as what angle the RF wave front
is incident on the water and how conductive the water is.  I can tell you
that based on my experience and expertise that even 72 MHz will not
penetrate very far unless the water is very pure (nonconductive).  A few
inches maybe.  If you want to penetrate 6 feet you are talking about a
frequency well below 1 MHz.  I know that the US Navy used to and maybe still
does communicate with submerged submarines at a frequency in the 10s of kHz
range.  Even then they use huge antennas (miles long) and huge power (many
megawatts) to enable reliable communications.

For your RC submarine model I would assume that the antenna floats on the
surface somehow but the information on the website isn't very clear on that.
I don't see how it could work otherwise.

73
Jim, W4KXY

-----Original Message-----
From: fourlanders-bounces at contesting.com
[mailto:fourlanders-bounces at contesting.com] On Behalf Of
whensley11 at comcast.net
Sent: Wednesday, October 26, 2011 9:37 PM
To: Fourlanders
Subject: [Fourlanders] RF and water

OK... the subject is RF and water... as in, how far into the water will a
signal go? 

If you had the choice between 72 MHz. and 2.4 GHz. what one would be best to
use? 

Depth? Not more than 6-feet... hopefully. 

So, why does Kim ask? 

http://www.engel-modellbau.eu/catalog/index.php?cPath=3_82&osCsid=namoo46sh7
mg7eovqs9pjdvki3 

Tnx & 73, 

Kim - WG8S 
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