Mike-
Thanks, much. It is interesting that, as far as I can recall, yours is the
first reference (Directly) to the QST article. I had forgotten it (Senior
moment?) I must go back and re-read.
About the radials-- I saw an indirect reference that the radial field was an
FCC REQUIREMENT. (?) I am not impressed by the expertise shown by the WWV
web site.
I still see (in my own mind) confusion in terminology concerning the terms,
1/2 wave monopole; 1/4 wave vertical with skirt; 1/2 wave vertical Dipole;
etc. I need to check some more in some Handbooks, and maybe Kraus. More
re-reading. It seems to me that calling their antennas "1/2 wave dipoles"
is incorrect.
Bill--W4BSG
----- Original Message -----
From: "Michael Tope" <W4EF@dellroy.com>
To: "Bill Aycock" <billaycock@centurytel.net>
Cc: <towertalk@contesting.com>; "N7mal" <n7mal@citlink.net>; "John Geiger"
<aa5jg@yahoo.com>; "Robert Redmon" <k5sm.bob@gmail.com>
Sent: Monday, April 06, 2009 12:25 PM
Subject: Re: [TowerTalk] Vertical vs Beam
> Bill Aycock wrote:
>
>> As far as the subject of 1/2 wave verticals goes, the WWV site leaves
>> out a LOT!
>> 1. Where is the feed point?
>
> The upper 1/4 wave of the 1/2 wave monopole is insulated. The antenna is
> fed with coax at this point against the skirt wires. This is described
> in the QST article and can be scene in the picture link of the WWVH
> antenna that W4TV posted.
>
>> 2. what is the feed point impedance?
>
> The article says 50 ohms.
>
>> 3. Are the lower ends of the "guys" grounded?
>
> No, the article indicates they are insulated
>
>> 4. Why is it important that the Coax feeds do not cross?
>
> Makes for a neat installation, but I can't imagine that it makes any
> difference to performance whatsoever.
>
>> Does anyone know?
>> Are the arrangements of the TTers with 1/2 wave verticals like WWV,
>> and if not, why reference it?
>
> Probably not exactly, Bill. I thought the point in the article QST where
> they mentioned the ground radials not impacting feedpoint impedance
> somewhat paralleled N3OX's experience. The article also mentions the
> expected gain over a 1/4 wave monopole (1.7dB).
>
> One interesting thing is that per the picture link that W4TV posted,
> they elected to use ground radials in the WWVH installation, but they
> did not in the WWV installation (the QST article claims that when it was
> determined tha the radials didn't effect input impedance it was decided
> not to include them in the installation). Perhaps radials were added
> later at WWV (my understanding is that they were only included for the
> two backup broadband monopoles antennas). I would be interested if
> anyone can confirm this. This speaks to previous discussions as to what
> field strength benefit is derived by including radials under a 1/2 wave
> vertical dipole.
>
> 73, Mike W4EF...........................
>
>
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