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Hi,
 Yes, the Aluminum Foil crunched up in the mast was
recommended for those making hollow wooden masts, that,
it was recognized, would not give much of a radar reflection,
if any at all.

Some 30 years ago I bought a "Firdel Blipper" radar reflector
(looks like a 12 inch diameter cylinder with rounded ends,
about 2 feet long).  When raised up in the rigging, and when
I was proceeding down the Intercoastal Waterway in Texas, USA
The barge tows I met never looked like they were surprised...
even "around corners" of the channel they knew I was there
before they could see me.  This was long before I had VHF radio,
and I did have a wooden mast, though a solid one.  (Very old boat
-
Tahiti ketch, built in 1941.)

 The Firdel Blipper is supposed to have a
rigid array of thin aluminum plates at right angles to one
another so that they give the best reflected return... like a
lens on an automotive tail-light, or those plastic reflectors
on automobiles.  Is the array (rain catching side up) honeycomb?

When I worked for a geophysical company offshore in the Gulf
of Mexico we sometimes put our bouys to re-calibrate radio
navigation...(LORAC) (This was in 1971. No GPS... and LORAN
was not accurate enough for our purpose.)
The bouys were cubic chunks of foam, with an 8 ft (just under
3 meter) bamboo pole through the foam weighted on one end... and
a plastic flag on the top.  I tried adding some aluminum foil
to the top, rather like a flag, to help finding the bouy in the
morning with the radar... It turned out that this was no help
at all, as a single sheet of aluminum seemed to be invisable...
was the frequency wrong, or did the sheet shape scatter the
radar signal off so that it did not return?

Anyway - lesson learned was that just a bit of metal in the
air did not make a good radar reflector.

Gerard Mittelstaedt    mitt@hiline.net
McAllen, Texas
USA

Peter Fogg wrote:
>
> ----- Original Message -----
> From: "Jared Sherman"
>
> >  simply cannot work. The
> usual heavy aluminum mast is radar opaque, nothing inside it could make a
> difference.
> >
>
> That makes sense. I wonder if what I'm remembering was a home-made radar
> reflector from the days of wooden masts.
>
> >  Unless someone has gotten a local exemption from the laws of physics ...
>
> This is a good idea, worth exploring further ...

--
---------------
Gerard Mittelstaedt    mitt@hiline.net
McAllen, Texas
USA

   

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