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(meteorobs) Meteor Scatter
This weekend I went to Waubaushene, Ontario, Canada (on the shore of
southern Georgian Bay).
Although the trip (about 1-1/2 hours drive away) coincided with the
Draconids, my main purpose for going was to get away from the congested FM
band conditions in Toronto. It worked! As any of you who live away from a
large city know, the radio detection of meteors using the FM broadcast band
is much more enjoyable and satisfying when you're not fighting your way
through dozens of stations and the associated adjacent channel problems.
However, all was not perfect. Having been up there last month 'to test the
waters' (the FM waters, that is), I had decided to listen for meteors on
101.5 MHz. But the tropo got to me this time around. So, I switched to 89.3
MHz. My initial reason for choosing 101.5 was that there are 5 stations
directly to the south that are good meteor scatter candidates (based on
distance, direction and power): WRAL (97 kW in Raleigh, NC); WORD (47.5 kW
in Pittsburgh); WAYZ (50 kW in Hagerstown, MD); WQUT (100 kW in Kingsport,
TN); and WBQB (50 kW in Fredericksburg, VA). There are only 3 good
possibilities on 89.3--one of which runs fairly low power: WQED (43 kW in
Pittsburgh); WPER (12.5 kW in Ashboro, NC); and WTNC (98.5 kW in New Bern,
NC).
Despite this minor setback, the listening was great.
Along with the stress-free listening conditions, I wanted to try out a
portable antenna setup to use a short yagi antenna. Of course, the yagi
isn't the problem; the problem is getting it up in the air. I based the
mast design on a concept developed for use at the Ontario DX Association's
listening camps by Jack Henshaw. I used two 6-ft. (2 m) lengths of ABS
pipe--one 1-1/4 in. (30 mm) and the other 1-1/2 in. (37 mm)--to build a
12-ft. (4 m) mast. In the assembled mast, the two pipes are held together
with a coupling adapter. A hose clamp at the top end of the mast holds
three 18-ft. (6 m) lengths of polypropylene rope in place to act as guys. I
use three 10-in. ( 25 cm) spikes as guy anchors and the mast sits on a
fourth spike to keep the bottom from popping out of position. Two U-bolts
hold the antenna in place. Unassembled, everything fits into the car
easily. The whole antenna takes me about 20-25 minutes to put up (or take
down) in the dark. Because the pipes are lightweight, it is easily a
one-person job.
For the listening project this weekend, I pointed the antenna straight up
toward the zenith. As usual, the individual elements were oriented
east-west so the antenna could 'listen' for stations to the south.
Fortunately, the sky was clear, so I could aim the antenna using Polaris as
a guide. (No, I didn't need a guide to point the antenna straight up! I can
do that myself. <|:-) But I did need Polaris to make sure the elements
were oriented east-west.)
I fed the antenna into two 10-dB r.f. amps and then into the
receiver--something that in Toronto would have only led to worse listening
conditions (if that's possible).
The weekend expedition was also a test of a system in which a power
inverter was used to convert the car's 13-volt DCsystem to 120-volts AC
needed by the receiver and the r.f. amplifiers. This worked well as long as
the receiver was located well away from the inverter. Otherwise, hash from
either a switching circuit or the inverter's oscillator got into the
receiver.
All said and done, the expedition was successful. The mast worked, the yagi
made a difference to the number of received signals and to the signal
strength (compared to the dipoles I usually use), the amplifiers helped
enormously, the mast makes portable operation using a yagi at a remote site
practical, and I was able to verify that it is feasible to detect
over-the-horizon stations via meteor scatter by pointing the antenna
directly toward the zenith. This is the initial step in comparing received
signals at various antenna elevation angles. The test also showed that
pointing the antenna straight up did not eliminate tropo, but that may be
due to the yagi's side lobes and/or the additional gain from the two r.f.
amplifiers. It's impossible to say at this time if the tropo was less of a
problem with the antenna pointed straight up compared to when it is pointed
at the horizon. But it would seem reasonable that pointing the antenna
straight up would at least reduce interference.
So...the Waubaushene Project continues next weekend (October 16)--likely
0700 UT Saturday morning. With an hour to set up the antenna and the
equipment--and troubleshoot, if necessary--listening will start at 0800 UT.
The next step in the project is to listen AND WATCH for meteors
simultaneously. If you would like to join me (I can use the help), you are
welcome to come along. Same location as this weekend. (See 'Directions' at
the end of this message.). As long as it is not raining, we'll press on. If
the sky is overcast, we'll do meteor counts to determine how many
reflections are strong, moderate or weak. Remember: dress warmly, bring
something to drink and snack on, and bring a reclining chair so you can
watch the sky as you listen.
Coming Up: The Temiscaming Backscatter Project, October 21/22; Location:
Temiscaming, Quebec (specifically, Auberge Canadienne, 1640 chemin Kipawa,
tel. 1-877-627-3111); Purpose: to listen for meteor-reflected signals from
stations to the south by pointing a yagi antenna toward the north at an
elevation of 70 deg. Anyone who wants to participate is welcome to come
along and join in.
Directions (to Waubaushene from Toronto)
Specifically, I will be at Government Dock #4. An Ontario road map will
make the trip straightforward. There are two possible routes depending on
your starting point. You can take Hwy 12 north to Waubaushene. (Many of the
highway marker signs will refer to Hwy 12 West rather than Hwy 12 North.)
The only tricky part of this route is the section of Hwy 12 just south of
Waubaushene. Even relatively recent Ontario Ministry of Transportation maps
and CAA maps show Hwy 12 (just south of Waubaushene) going through
Fesserton. Hwy 12 has been re-routed (to bypass Fesserton?) and now joins
Hwy 400 at interchange 141. The two highways separate again at interchange
147 which is the exit to Waubaushene. Waubaushene is just a kilometre or
two from the highway exit.
The other possible route is up Hwy 400. Taking this route, you also exit at
interchange 147.
Once you exit Hwy 400/12 (but continue along Hwy 12 West), the exit ramp
curves around and then under
the highway overpass. Just beyond the overpass, you will see a green and
white sign indicating
Waubaushene and Pine Street. Turn right at Pine St. The second street along
Pine St. is Coldwater
Road. Turn right onto Coldwater Rd. Follow this road to Government Dock
Road. Turn right on Government
Dock Rd. This is a very short, curving road which leads to the dock.
If you become lost in Waubaushene, don't worry. It is a very small town and
anyone will be able to direct
you to the dock.
Phil Gebhardt
pgebhardt@compuserve.com
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