Re: [amsat-bb] True bearings vs. magnetic
I don't think its all that critical based on what I see here:
http://www.dx-antennas.com/Yagi3.htm
73 John KI4RO
You bring up an important point regarding beam width. The link provided shows a 3 element with 100° width so you need to be within 50° of either side of center to be inside the front lobe.
Now consider a V/UHF beam that can have 3-5x as many elements. Say for instance you’re at 30° beam width or 15° to either side of center. If the station is off by 12.5° they are almost completely outside the lobe.
With my 5x9 Arrow I notice just how much more accurate I need to be when pointing over the 3x7 Arrow II if I want maximum gain.
That said, just how important it is to be true north versus magnetic north is going to depend on your beam width.
73, Mike Diehl W8LID
On Jun 3, 2018, at 12:10, John KI4RO johnki4ro@gmail.com wrote:
I don't think its all that critical based on what I see here:
http://www.dx-antennas.com/Yagi3.htm
73 John KI4RO _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Your example is a 3 element CB beam. That is a FAR cry from even the smallest yagis that are routinely used for VHF & UHF satellite operating. Personally, I run 22 elements on 2M and 40 elements on 430. Back on AO-40 on 2.4 GHz, I was running a 2 x 3 foot dish. I can guarantee you that with high performance antennas, the difference between magnetic and true heading would make a large difference.
The VHF and UHF antennas (photo taken before the dish was added): http://members.dslextreme.com/users/k6ccc/Photo/Pics/SatAnt1.html And one after the dish was added: http://members.dslextreme.com/users/k6ccc/Photo/Pics/S-band1.html
And yes, before someone points it out, it's been years since I was active. Several reasons for that. One of these days, I will be back...
73 Jim Walls K6CCC jim@k6ccc.org
-----Original Message----- From: "John KI4RO" johnki4ro@gmail.com Sent: Sunday, June 3, 2018 09:10 To: amsat-bb@amsat.org Subject: Re: [amsat-bb] True bearings vs. magnetic
I don't think its all that critical based on what I see here:
http://www.dx-antennas.com/Yagi3.htm
73 John KI4RO _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (3)
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jim＠k6ccc.org -
John KI4RO -
Mike Diehl