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Topband: Power Coupling in the USA

To: <topband@contesting.com>
Subject: Topband: Power Coupling in the USA
From: btippett@alum.mit.edu (Bill Tippett)
Date: Sun, 05 May 2002 12:07:59 +0100
Hi Steve!

        I don't want to get into an anecdote contest with anyone
but would just like to factually correct something you wrote.  I'll
summarize my opinion by simply saying:

1.  Vertical antennas are better DX antennas than low dipoles.
2.  Any dipole less than 250' high is low (<0.5 wavelength).
3.  Any 160 antenna (dipoles included) is better than no 160 antenna!

                                                73,  Bill  W4ZV

VK6VZ wrote:

>The other thing to note is that those DXexpeditions who equip themselves
>with the great Battle Creek Special - an inverted-L antenna - get as much
>radiation above 45 degrees as they get below it.  The BCS gets a lot of
>credit as a low angle radiator, but it is also a good high angle antenna on
>160m, with appreciable horizontal polarised radiation.

        This is incorrect.  You are probably thinking about a 3/8 wl 
inverted-L which is indeed a high angle antenna.  The BCS is a loaded 
50' high 1/4 wl inverted-L with approximately 70' horizontal.  Over good
ground, EZNEC shows the 3 dB power points at 8 and 56 degrees with the 
maximum at 25 degrees.  Over very good ground, it the 3 dB points are 4 
and 52 degrees with the peak at 19 degrees.  I'm not taking the time to
model the on-ground radials it actually uses but I would estimate its  
performance lies between the two results given.  BTW, W8JI and I also
have poor ground conductivities (2-4 mS/m) and the same was true for
my location in Colorado.  Fortuntely a good radial system can overcome
any ground conductivity for near-fields.


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