From: Jeffrey Lomicka <JeffreyLomicka-AT-comcast.net>
Date: 02 Jul 2009 06:31:51 UTC   (09:31:51 AM in author's locale)
To: xtensionlist-AT-shed.com

I haven't tried this, but I've been thinking about putting one of my
temperature sensors at the focal point of a parabolic reflector. You
might be able to locate the motion sensor at the focal point of a
reflector pointed at your receiver.

I did this with a WiFi receiver and it seemed to significantly help the
directional range.

There are a few web sites that let you download templates for making one.
I used this one:
www.freeantennas.com/projects/template/index.html

but there are others, like this one:
binarywolf.com/249/diy-parabolic-reflector.htm

It also helps to fine tune the transmitter to be sure the signal is as
close to 310Mhz as you can get it. I tuned mine in a lab at work, using
a spectrum analyzer, and gently bending the "tuning coil" inside the
thing. There are other ways that involve walking out of the range of
the transmitter, then tweaking to see if you can get it to work again,
then walking out further, etc., until you can't get it any better. I
was able to go clear across the street with a motion sensor, but I can't
say for sure it was 300 yards.

An option on the receiver side is to use a TV signal amplifier between
the W800 and it's antenna. My RFX and MR10 are both behind an amplifier
attached to an omni directional high gain scanner antenna, and this has
helped a lot, even with the antenna in the basement.

For 300 yards, you might need all of this stuff and then some.

What would happen if you put the scanner antenna on the motion sensor?
Legal issues aside, what about the scanner antenna with the amplifier in
backwards (like a linear power amp)?

Jack Stewart wrote:
> I wonder if anyone here has ever attempted an antenna hack of the MR14A motion sensor with the objective of achieving an increase in range?
>
> I would like to use MR14's in a detached building about 300 line-of-sight yards away from the W800 antenna. I do not want to make the W800 antenna directional so this seems to be the only alternative way to achieve improved range.
>

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