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Author Topic: Antenna Radiation on Map  (Read 11177 times)
KG6Q
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Posts: 64




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« on: August 03, 2013, 06:46:47 PM »

I'd like to overlay my antenna radiation pattern, centered on my QTH, onto a world map. This would easily allow me to determine which countries I am most likely to work and at the same time, which countries I'm least likely to work.

Anyone know of a simple way to do this or of any ham mapping software that can do this?

KG6Q (formerly KJ6ELD)
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W4TRJ
Member

Posts: 19




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« Reply #1 on: August 04, 2013, 07:40:53 PM »

This doesnt answer your question, exactly, but have you looked at the reverse beacon site?

http://www.reversebeacon.net/main.php

It is very helpful (and surprising to me, at least) in determining where a signal is reaching.

I do cw, no idea if it works on sideband, or if you do cw.

Anyway, might be helpful to look into it. Just do some transmitting, then put in your call sign and see where you're being picked up. I routinely hit europe on 20m with 100 watts and a g5rv at 42 ft from South Central GA.

DC.
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K0OD
Member

Posts: 2591




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« Reply #2 on: August 05, 2013, 06:36:42 AM »

What sort of antenna are you using? What bands?

When I used a 4-square vertical array I used narrow black tape to form a large X on my framed ARRL World Map to show my four possible peak (and four null) directions. But that array was quite directional and switchable. 

If you're using something like a high dipole you'd be concerned with the nulls off the ends. Low dipoles are fairly omnidirectional. In any event, DX paths vary. 
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K6AER
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Posts: 3535




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« Reply #3 on: August 06, 2013, 09:08:56 PM »

Antenna patterns widths  are determined at the -3 dB point. Most beams are about 90 degrees  for a 3 element and 60- degrees for a wide spaced 4 element. Pointing the beam at Europe will enable you to work stations from Russia to the Mediterranean. It just is not that critical.

Run 1 KW with a beam a 80 feet and you will have a S9 plus 20 signal in most of Europe. The pattern is just not critical.
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KB4QAA
Member

Posts: 2490




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« Reply #4 on: August 25, 2013, 06:47:52 AM »

I don'dBt know of a way to combine plots graphically on a computer.

The best way to visualize your pattern is to run an analysis on EZNEC or other program with the 3dB markers turned on.  Then either lay the pattern on a paper map, or 'eyeball integrate' it with a display on your monitor.
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WB6BYU
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Posts: 13586




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« Reply #5 on: August 25, 2013, 09:07:08 AM »

You can start with an azimuthal map centered on your QTH from NS6T's web site here:
http://ns6t.net/azimuth/azimuth.html

You can print out radiation patterns from EZNEC and other simulation programs.

Now I haven't yet figured out how to overlay them easily.  I suspect you'll need to modify
the radiation pattern plot to have a clear background rather than white, then pull both
images into a graphics program to overlay them.  I tried to do it in a PowerPoint presentation
and didn't get it to work in the time I had available.

One issue with this approach is that you really need to look at a 3-dimensional pattern
because different distances will have different optimum vertical angles:  an azimuth
pattern taken at any one elevation angle won't really be correct for all distances. 
I think you can get a data dump from EZNEC in some format that would allow you to
process it in a spread sheet, for example, that would calculate signal strength at a distance
based on the required vertical radiation pattern in the pattern, but that gets more complicated.

And, of course, standard patterns are based on flat ground.  If your ground isn't flat then
something like the HF Terrain Analyzer software will give you a better idea of how the ground
affects the signal strength vs. bearing and distance.
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N5OTH
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Posts: 6




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« Reply #6 on: August 25, 2013, 03:29:34 PM »

WB6BYU -- That map shows me to be located in the Southern part of the Gulf of Mexico.  I live near Lafayette, LA. Huh
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Dennis, N5OTH
WB6BYU
Member

Posts: 13586




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« Reply #7 on: August 25, 2013, 09:44:22 PM »

What did you enter for your QTH location?  You can use the nearest major city (that
should be close enough for most purposes) or provide Lat and Long.  I tried typing in
"Lafayette, LA" for the QTH and the center of the map is in south-central LA - at least
it is on land.
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N5OTH
Member

Posts: 6




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« Reply #8 on: August 26, 2013, 05:11:43 AM »

WB6BYU -- I entered my Grid Square as EM40ai.  I will try Lafayette, LA and see what comes up.  Thanks.
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Dennis, N5OTH
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