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[TowerTalk] FW: Magnetic Declination

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Subject: [TowerTalk] FW: Magnetic Declination
From: (
Date: Sat, 22 Sep 2001 14:49:06 -0600
On Sat, 22 Sep 2001  Pete Smith <> writes:
> At 12:41 PM 9/22/01 -0400, Dave, AA6YQ wrote:

> I probably should have made this point earlier, but working to this 
> level of precision is pointless for HF antennas, typically with 1/2
> beamwidths of 30 degrees or more.  That's why I hoped we could avoid
> resurrecting the True North thread again.

        Actually, the - 3dB beamwidth of a 5L Yagi on a .75WL
        boom is closer to 50+ degrees.  The beamwidth of a
        3L Yagi is closer to 60 degrees.

        Another interesting observation is that the signal level
        at +/- 45 degrees is roughly equal to that of a dipole
        for 2 to 5 element Yagi's.  The 3 dB beamwidth's are
        less for more gain, but the absolute levels at +/- 45 degrees
        appear to be about the same (+/- a dB).

        Tom  N4KG

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