From: ch.steyaert@abbs.hanse.de (Chris Steyaert)
Newsgroups: sci.astro
Subject: Radio observation of meteors
Reply-To: ch.steyaert@abbs.hanse.de
Date: 08 Nov 92 20:55:00 MET
Distribution: sci
Organization: ABBS AstroMail, D-W 2121 Dahlenburg / Germany
X-Version: ZerUU V6.45c

From time to time the subject of observing meteors by means or radio is been
discussed in this newsgroup.  A few months ago, the article of J. L. Lynch
in Sky & Telescope, Aug 1992, 222-225, has been discussed here too.
The statement "Because of their height, meteors best reflect signals from
800 to 1300 miles away from you" has been scrutinized, but no final answer
has been given as far as I remember.

It is not correct, as the received power is inversely proportional to

        R1 * R2 * (R1 + R2)

 with R1 = distance transmitter - reflective point on the trail
      R2 = distance receiver    -     "        "

all other factors remaining the same (not considering some geometrical
factors).

The limiting case is "backscatter", whereby the transmitter and receiver
coincide: this is the radar set-up.

Forward radio scatter is much more difficult in crowded Europe than e.g. the
midwest of the US.  All FM frequencies are being re-used a few hundred
kilometers apart.  The best thing to do is point the Yagi antenna vertically
or at high elevation, in order to avoid picking up nearby stations. On the
same token, the antenna should not be on a high mast, and ideally be located
in a valley (a bit like the Arecibo antenna being in a valley, although not
only for interference but also construction reasons in this case).

One way out in Western Europe is to tune to FM stations in the former
eastblock, who are broadcasting in the range 66 - 73 MHz (and vice versa).
These frequencies are not in use locally.  But no off-the-shelf radio tuners
are having both frequency bands (not speaking about radio amateur gear with
all band coverage).

The International Meteor Organisation has a Radio Commission, which is all
about this type of forward scatter observations.
There are now a few proofreading copies available of the forthcoming
publication

    "Radio Observation of Meteors", edited by Jeroen Van Wassenhove

    with contributions of P. Brown, W. H. Black and the undersigned

    Contents:

    Introduction
    Some history
    Basic Theory
    Equipment set-up
    Observing in practice
    Reduction of data
    Automated Forward Scatter Systems
    Advanced radio echo theory
    Meteor showers
    Abbreviations
    Appendices
    Software

For further information, please contact Jeroen at

    Jeroen Van Wassenhove
    's Gravenstraat 66
    B 9810 Nazareth
    Belgium
    E-mail: Jeroen.Van.Wassenhove.f852.n292.z2.fidonet.org


or leave a message to me, which I will pass on to him

--

Chris Steyaert
Dr. Van de Perrestr. 83
B 2440 Geel
Belgium
fax (32)14 22 13 73
              
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