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<div class="moz-cite-prefix">Steve,<br>
<br>
Nice. One thing, though: Your calculation seems to assume that
all of the power at the target depth ends up in the receive
antenna. That's not going to happen. But I suppose the good news
:) is that the attenuation through the ground is so high that the
additional loss due to the small size of the receive antenna
probably only amounts to a change of a few skin depths.<br>
<br>
-Les W6VN<br>
<br>
<br>
On 11/21/2012 10:18 PM, Steve Noskowicz wrote:<br>
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<div>I did some back of the envelope
calculations...Well... Excel anyway.</div>
<div> </div>
<div>Looking at the Skin depth chart for 'earth' in the
Speleonics newsletter #1 gave me an idea.</div>
<div>Calculate the path loss of earth on 160 meters using
skin depths.</div>
<div> </div>
<div>Given that one skin depth has 8.7 dB of loss...</div>
<div>And assuming you can get a full 5 watts power into
the ground at the Tx surface...</div>
<div>And assuming you can get all the energy out of the
ground at the receive "end".</div>
<div> </div>
<div>Looking at the Skin depth chart for 'earth' in the
Speleonics newsletter #1...</div>
<div>The middle curve of .01 mhos/meter of ground
conductivity shows a skin depth of about 4 meters at 2
MHz.</div>
<div> </div>
<div>With a receiver sensitivity of -110 dBm (0.7 uV) this
is a path loss capability of 147 dB.</div>
<div> </div>
<div>Which translates to 17 skin depth or 222 Feet.</div>
<div> </div>
<div>Using the "best" conductivity curve (0.001 mho/m) I
get 888 feet.</div>
<div> </div>
<div>These must give a rough estimate of some sort of an
upper limit for through-earth radio ... in rough
numbers, very rough, of course....</div>
<div> </div>
<div>There is also a lot of info on low freq Magnetic
communications in those newsletters.</div>
<div> </div>
<div>73, Steve, K9DCI</div>
<div> Fun exercise.<br>
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