[GeoStL] Re: Question for Garmin eTrex users

Hold it horizontally, and most importantly, keep your fingers off and away
from the top 1/3 of the unit. And try and keep it a bit away from your body.

The Etrex has a microstrip patch antenna. If you have an Etrex Legend with
the translucent body, you can see it as a 1" x 1" square at the top under
the globe logo.

Patch antennas receive best in the direction that is normal to their flat
surface. I.e, "up, if the unit is held flat". They do receive in all
directions, but not equally well. If you want it to have the best chance of
seeing everything up in the sky, hold it flat. I attached to this message a
.jpg image of a field plot of a typical patch antenna. If it worked equally
well in all directions the plot would be a circle. In this case, the up
(good) direction is to the right in the picture (what you'd get if you held
the unit vertical). Guess I should have rotated it 90 degrees CCW.

Ever wonder what it is that makes your signal drop out when your in the
forest? Of course we've all figured out its all those leaves up there. But
it's predominately the WATER in those leaves that's doing it.

Try these experiments:

a) Put an Etrex outside on a table, on the Satellite screen. Let it acquire
the birds and stabilize. Watch the signal strength bars across the bottom.
Place your thumb or 2nd and 3rd finger on top of the patch antenna (put them
on the globe symbol). Over the next 10 seconds watch the signal strength
bars melt away. Bye bye signal. Remember this next time you use it! Keep the
fingers away!

b) Repeat this experiment, but this time instead of using your fingers put a
small plastic glass filled with, say 1/2" water over the globe and watch it
absorb your signal.

c) If anyone wants to stand out in pouring rain and report back if signal
strengths go down that would be interesting :)

As far as getting better results holding it vertical - that could be a side
effect of in doing so your fingers aren't over the top of the antenna, or it
is more in the clear above your body, depending on how you hold it.

John


----- Original Message -----
From: "Paul Konopacki" <konopapw@xxxxxxxxxxxxxx>
To: <geocaching@xxxxxxxxxxxxx>
Sent: Thursday, August 29, 2002 11:04 PM
Subject: [GeoStL] Question for Garmin eTrex users


> "I did have some trouble keeping a satelite lock til I
> read a post that said if you hold it horizontaly it tends
> to lock in better. Since then I've kept my lock in the
> woods no problem."
>
> True statement?
>
>
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Attachment: fieldplot.jpg
Description: JPEG image

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