[Elecraft] OT: Elevated vs. Buried Radials

Sun May 19 16:59:50 EDT 2013

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 <wunder at wunderwood.org>:

> 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" <lists at 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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>> 
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> 
> --
> Walter Underwood
> wunder at wunderwood.org
> 
> 
> 
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