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Author Topic: Angle of signal departure  (Read 708 times)
KF7RMO
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« on: March 13, 2013, 07:32:44 PM »

My QTH is located in a deep canyon. The walls are about 1,000 ft high. My problem is determining what angle/path the signal takes to the reflective layers of the ionosphere at 20 - 80 meters. Have searched the net for info without success. Before I invest alot of time setting up antennas, I'd like to know if it is a worth the time and $. Any help would be greatly appreciated.
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WA3SKN
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« Reply #1 on: March 14, 2013, 04:40:56 AM »

You might be suprised at how well you get out.  What you need is a nearby ham that can bring some eqpt with him and do some tests... all the theory in the world will be of little help as to your situation.  Are there any clubs in the area that could help?  Many hams would like a mini "Field Trip" to set up and operate at a challenging location!

-Mike.
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WB6BYU
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« Reply #2 on: March 14, 2013, 08:13:49 AM »

Quote from: KF7RMO
My QTH is located in a deep canyon. The walls are about 1,000 ft high...

How far away are the walls?  The vertical angle to the top is what really
matters rather than the vertical height.  If the wall is 1 mile away then
the vertical angle is arctan(1000/5280) = 11 degrees, and you should
be able to work plenty of DX on 20m at that angle.

Out the ends of the canyon you often have an even lower horizon.

On 80m for relatively local contacts, high angles of radiation are quite
effective:  you should have good signals out to hundreds of miles from
a relatively low dipole when the ionosphere is cooperative.
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N4JTE
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« Reply #3 on: March 14, 2013, 04:47:05 PM »

I live at 230ft abs in the hudson valley of NY and out ALL of my windows I have 2000 ft hills about a mile away.
I have used almost every conceivable wire antenna on 160, 80, 40 and never had a problem getting "over" the surroundings to stateside, Europe, New Zealand etc. I would just build the best antenna you can and carry on, besides moving, I don't see any other choice.
On two meters the mountains occasionaly interupt the path but I really have nothing to add to the usual pick up dinner conversations on that band so no great loss.
Bob
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K8AXW
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« Reply #4 on: March 14, 2013, 06:02:25 PM »

Bob:  I don't  wish to highjack this thread but people in our area of WV have the same problem. 

I suggest you swing the beam around and bounce your 2m signal off the mountains, towers, telephone dishes..... to get to repeaters you want to hit.  Works here!
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N1UK
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« Reply #5 on: March 15, 2013, 10:22:04 AM »

Read this..it might help

http://stationproject.wordpress.com/tag/hfta/

Quote
The Purple bars at the bottom of the graph show the probability that a station in Europe will arrive at a given T/O angle. You can read the actual probability for a given T/O angle bar on the right vertical scale as a percentage. Note that this part of the data is based upon predictions and actual measurements over a range of sunspot levels across the entire 13 year sunspot cycle. Note that this does not mean that the band will always be open; rather the bars indicate the probability that a station from Europe will arrive on a given angle if the band is open.

Note that the single most important arrival angle is at 1 degree which accounts for almost 8% of all contacts. This is common and speaks to the importance of engineering an antenna system which performs well at low T/O angles. Also note that our planned system does a reasonably good job of covering all T/O angles from Europe in this direction.


So the ionosphere will support all sorts of propagation angles which are always changing.

Mark N1UK
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