Radial straight down
 

Has anyone ever bored a hole into the ground and dangled a radial or
counterpoise down it instead of burying a radial 6" horizontally under the
ground or stringing out a counterpoise?

Any promise in doing this? Or is it a non-starter?

Radial straight down
 

Richard wrote:
Has anyone ever bored a hole into the ground and dangled a radial or
counterpoise down it instead of burying a radial 6" horizontally under
the ground or stringing out a counterpoise?

One of my textbooks says such a configuration
dissipates half of the incident power.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Radial straight down
 

"Richard" wrote in message
...
Has anyone ever bored a hole into the ground and dangled a radial or
counterpoise down it instead of burying a radial 6" horizontally under the
ground or stringing out a counterpoise?

Any promise in doing this? Or is it a non-starter?

Well, I have a 1/2 wave inverted L for 160 that I use with a remotely tuned
L network on 160, 80 and 40. The matching network sits on top of a 6 inch
well casing that goes down 90 feet and is grounded to that. That was
initially my only ground. The 160 meter impedance was 2600 Ohms and 1800 on
80 and 700 on 40. I later installed a counterpoise under the horizontal
portion of the antenna, 160 feet at 10 foot elevation. Of course, I didn't
notice any change in operational reports or anything, but the feedpoint
impedance went to 1900, 1200 and 450 Ohms respectively. I suppose the
earthworms think that global freezing is taking place, but no other effects
noted. It's been a very effective LF antenna for over 20 years both ways.

W4ZCB

Radial straight down
 

Richard wrote:
Has anyone ever bored a hole into the ground and dangled a radial or
counterpoise down it instead of burying a radial 6" horizontally under
the ground or stringing out a counterpoise?

Any promise in doing this? Or is it a non-starter?

Radials basically serve the purpose of improving the apparent
conductivity of the soil at the base of the antenna (e.g. less loss than
a simple stake in the ground).

A goodly portion of the loss of an antenna like a vertical is in the IR
losses of the RF current flowing in the surface of the soil (where
"surface" depends on the RF properties of the soil, skin effect and all
that).

So, burying deeper probably doesn't help this (e.g. you want to improve
the conductivity at the surface).

Radial straight down
 

On May 11, 8:23*am, "Richard" wrote:
Has anyone ever bored a hole into the ground and dangled a radial or
counterpoise down it instead of burying a radial 6" horizontally under the
ground or stringing out a counterpoise?

Any promise in doing this? Or is it a non-starter?

Letter from June 1949 QST:

Dear Editor: I have followed with great interest your articles and
correspondence on underground antennas.

I tried several directive beams buried in four feet of moist earth.
After several reports from various hams I found I had no more power
than with the old skywire. I dug deeper - even tried rhombics - but
reports were still the same ('Nice sig, OM, but some guy in Califormia
has 10kw right on you.')!!! I consulted the old faithful ARRL Handbook
and decided to try a multiple-wavelength vertical on ten meters.

I did not have to look far for a suitable antenna site. We have a 200-
foot well right in our basement. I hooked a variometer to the final
tank and from same connected a No. 6 stranded wire to a pipe running
into the well.

I was delighted to raise a C2 in Hankow, China, on my first CQ.
Chinese stations were heard that pinned the S-meter on the receiver.

I soon discovered that all I could work were Chinese amateurs. Now
wouldn't this bear out the Handbook theory that 'the more wavelengths
an antenna has, the more it tends to radiate straight off the end'? -
W7LLE

Radial straight down
 

On May 11, 7:23*am, "Richard" wrote:
Has anyone ever bored a hole into the ground and dangled a radial or
counterpoise down it instead of burying a radial 6" horizontally under the
ground or stringing out a counterpoise?

RF currents needing to travel a lengthy path through the earth to
reach such a vertical buried wire would encounter high losses.

The function of buried radials is to provide a low loss return path
for the r-f conduction currents induced in the earth near a monopole,
which result from displacement currents generated by radiation from
the monopole. Almost all of these currents lie within a radius of 1/2
of a free-space wavelength (regardless of the monopole height).

So the most efficient collection of these ground currents means the
radials should extend about 1/2 of a free-space wavelength from the
base of the monopole -- so that the currents won't have to travel very
far through the lossy earth before they are "captured" by a radial
wire.

The electrical length of buried radials with respect to the reduced
v.p. in their environment has no real bearing on how effective the
radials are at reducing the r-f loss in the ground system.

The r-f loss present in the radial ground system doesn't affect the
shape of the relative field pattern generated by the monopole, or the
propagation of the fields launched by the monopole. But as that
ground system loss is in series with antenna current, it will affect
the radiation efficiency of the antenna system.

A benchmark, real-world study of this subject was made by Brown, Lewis
& Epstein of RCA Labs in 1937. It showed showed that 113 evenly-
spaced, buried radials each 0.412 free-space wavelengths long and used
with monopoles from ~70 to 90 degrees in height produced measured
surface-wave fields at 3/10 of a mile that were within 2% of those
generated by a perfect monopole with a zero-loss r-f ground, over a
zero-loss ground plane.

This corresponds to an antenna system efficiency of about 96%, or 960
watts radiated for 1,000 watts applied to the feedpoint. For a
monopole with a radiation resistance of 36 ohms this 96% efficiency
means that the r-f resistance in the ground system is about 1.5 ohms.
There wouldn't be much practical benefit gained by using more/longer
radials.

The BL&E tests were conducted in the sandy soil of New Jersey, where
earth conductivity is rather poor.

RF