[aprssig] FW: Animal tracking using GPS+UHF

[Robert Bruninga]

Re: Detecting Dipole presence:

Actually, a more directive approach using what
we have, would be to use the TM-D700 mobile
rig which can transmit on 440 and RX on 1296.
This combination would allow much greater gain
and directivity in much smaller antennas, and
the "transponders" need only be about 13"
long... (or do we tune the dipole for the harmonic?)
Wb4APR

>>> bruninga at usna.edu 02/09/06 5:27 PM >>>
Regarding Tracking Animals:

I just read about "harmonic" radar for tracking
insects.  All you need is a dipole with a diode
in the middle of it.  It will convert an incoming
RF "illuminating" wave to a Harmonic for
detecion by a receiver tuned to the harmonic.

I'm wondering what cute thing we can do with
it with HAM radio.  Imagine, sewing a 37"
very thin wire dipole into the jacket liner of
all the Club Shirts of your radio club.

Now then at the door of any facility  you have
a receiver tuned to the 440 3rd harmonic of
a local repeater or some other 2 meter illuminating
source.  Whenever the squelch opens, you have
just detected the nearby presence of someone
with their club jacket on.

A poor-mans RF-ID, but it of course has no
"ID" capability.  Just presence. or not...
Now you COULD use this for tracking your
dog, if you have a powerfull enough 2m TX
(without harmonics)...  I wonder how many
hundred feet the range would be?

Hummh...

de WB4APR


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