Can we possibly get back to topics that are relevant to Elecraft
equipment. Find a different forum to talk antennas!
73,Tom (K7ZZ)
On Sat, May 18, 2013 at 11:36 PM, Oliver Johns ojo...@metacosmos.orgwrote:
ELEVATED RADIALS: I think Joe hits it on the head here. A vertical with
elevated radials is essentially an OCF dipole. There is no particular
reason for the radials to be a quarter wavelength. They should be
whatever length lets you resonate the antenna with a feed impedance you can
live with.
IMPT POINT: If you want your antenna actually to have a vertical
radiation pattern (low angle, omni-directional) then the elevated radials
must be symmetric. If there are two, they must be of exactly equal length
and point in exactly opposite directions. If there are four, they must be
equal and point in directions 90 degrees from one another. This symmetry
guarantees that the radials do not radiate. The do carry currents, they
do help resonate the antenna, but if they are symmetric radiation from them
cancels and they therefore do not radiate appreciably.
73,
Oliver
W6ODJ
On 18 Jan. 2013, at 06:46 AM, Joe Subich, W4TV li...@subich.com wrote:
Personally, I do wonder about the new fangled no radials required
antennas. But, I have an old R5 and it works well.
The no radials antennas are basically a vertical OCF - the short
decoupling radials are the short leg and the vertical is adjusted
through the use of traps, stubs and/or loading to resonate on the
desired band with the fixed length (typically 42) of the short
radials.
73,
... Joe, W4TV
On 5/18/2013 9:25 AM, Bill wrote:
The cleanest installation is to put the radials in the ground - but, not
portable at all. The idea is a capacitance connection with the earth. I
have used welded steel cattle fence in the past - I build a mat that is
about 30 or 40 feet out from the base of the antenna.
For raised radials - they must be resonate to function properly. Three
or four per band or related band. They have to be high enough that they
present no danger to anyone roaming around your antenna field. They can
be drooping or horizontal - both work well.
Personally, I do wonder about the new fangled no radials required
antennas. But, I have an old R5 and it works well. Perhaps the way to go
is a new antenna that just gets bolted to a post and a feedline
attached. Sure makes life easier and from folks I talk to all the time -
they do work. Forget that they are a little expensive. You buy an
antenna to use for years.
Read the eHam reviews and see what other users are saying before you buy
anything. Ask on the air.
The best I ever had was a Butternut of some kind over a bunch of buried
fence. Might still be the way to go. But, if I was doing it now, I'd be
looking at a no radials required antenna. My reasoning is somewhat age
related.
Be looking forward to the sage advice that will come from this post. It
is summer - so it is antenna time.
Bill W2BLC
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