Topband: elevated radial question

[Charlie Cunningham]

Hi, Grant!

Well, sometimes we have to just "flower where we're planted" and what is IS!

I actually think that an 85' high TEE with elevated radials will be an
excellent 160 antenna for you!!  Actually, I don't expect that
you really need 7 radials. Four should do fine! Of course,  you could add
more later. If you wish! I don't think you'll have much interaction between
your radials and the 4 square receive array since it is vertical, but if the
4 square array has radials you might try to keep them separated from  your
160 transmit radials. I used to have m y 160 inverted-L radials on my small
lot, along with my 80m GP radials and both worked great!

I surely would avoid contact between the 160 radials and that metal
building. Any contact would substantially alter the current distribution,
electrical length and resonance of the radials. All that can be checked with
some imaginative work with an antenn analyzer or dip meter.Note that if  you
connect any two reasonable opposing radials together near the feedpoint, of
your TEE, the pair should be 1/2 wave resonant.

I absolutely would NOT connect to the building  NOR would I  run the radias
over the metal roof! Just use FEWER radials! High conductivity is GOOD! Just
don't connec to it! BTW, you could also  hang and 80m quarter wave wire off
the flat topof  your tee and attach I to the same feed point as the 160
antenna. Of course you would also need to add some 80m radials!

Good luck!! Sounds lie it's likely to be a really good 160 transmit antenna!
-MUCH better than a delta loop~

Charlie, K4OTV



-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Grant
Saviers
Sent: Wednesday, December 12, 2012 7:06 PM
To: topband at contesting.com
Subject: Topband: elevated radial question

I'm finalizing the layout for a tree hung T loaded vertical for TB, about
85' to the top, two x 45' mostly horizontal loading wires, and radials
elevated 10' above (much?) better than average soil, at least this time of
year when I have standing water among the trees. (Redmond, WA)

I'm taking W8JI's advice and going with the top loaded vertical rather than
a delta loop, particularly after I determined I can squeeze seven fairly
symmetrical 130' radials in (with a cooperative neighbor).  I plan a
switched series capacitor feed for bandwidth, with the antenna resonant at
1815KHz or so.

Now two questions before stringing wire -

1. My new DXE 4 square receive array is outside the radial field, with the
center of the square 82' from the radials perimeter.  Does it matter if the
end of one radial is about 30' from a corner 4sq antenna, or should I pitch
the radials to maximize the separation? Even as much as a 90 degree (or
more) segment with no radials?  At 90 degree pitch the nearest radial ends
would be about 80' from their nearest 4sq antenna.

2. Now the unusual circumstance - there is a 56' x 70' steel building
entirely inside the radial circle, but at the perimeter. Steel roof, walls,
and Ufer grounded to the perimeter footing.  My thinking, not sure I'm
correct, is to NOT attach any radials to the building (12' to eves, 14' to
peak), but nestle it between 2 radials with about 15' feet of minimum
clearance.  OTOH, I can connect one or more radials to the steel, or run one
or more insulated radials over the roof to a support off the perimeter end
of the building. And then OTOH, the steel sure makes this part of the radial
field pretty high conductivity.  This one is definitely not in the handbooks
or in ON4UN or in the N6LF QEX articles. btw I have a SteppIR BigIR vertical
going on the center of this roof as a secondary/backup HF antenna.

Inputs appreciated,

Grant KZ1W

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