An oft overlooked advantage to elevated radials is that, properly
terminated, they will keep your hat from blowing off.
________________________________
John T. Gwin
[email protected]
[email protected]
----- Original Message -----
From: "Ralf Wilhelm" <[email protected]>
Cc: "elecraft List" <[email protected]>
Sent: Sunday, May 19, 2013 3:59 PM
Subject: Re: [Elecraft] OT: Elevated vs. Buried Radials
My today's experience was that my nice KX3/ATU which happily tuned my
random wire when running from a power supply two weeks ago refused to load
the same wire at the same location on all bands below 10 megs when running
from the internal battery. However, I could convince it to tune the
antenna while I was touching the case of the transceiver (I have been
doing some simulations In order to gain some understanding why the german
"Multiband-Fuchskreis" sold by a german Elecraft reseller seems to work in
some situations and doesn't work for others and just used what I learned
from my simulations)
Obviously the "counterpoise" was missing (or in my words the capacitance
of the case to ground was not high enough). I could not test if plugging
the headphones in and using them is sufficient to increase the capacitance
sufficiently ;-)
So, although not directly related to elevated radials, this former OT post
has a relation to Elecraft equipment now ;-)
BTW, is there any idea concerning the order of magnitude of the
capacitance of a human body (6ft tall, normal weight) with respect to
ground?
Vy 73, Ralf, DL6OAP
Am 19.05.2013 um 17:28 schrieb Walter Underwood <[email protected]>:
A vertical dipole can be balanced with the lower element shorter. It will
have more capacitance to ground, which makes it electrically longer. This
is like putting a capacitance hat on the end of an element.
wunder
K6WRU
On May 18, 2013, at 11:36 PM, Oliver Johns wrote:
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" <[email protected]>
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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--
Walter Underwood
[email protected]
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