Use of ground wires underneath dipoles
 

According to Wikipedia
(http://en.wikipedia.org/wiki/Near_Ve...dence_Skywave), a
horizontally-polarized NVIS antenna will benefit from a ground wire
underneath it.

Here's an excerpt:

"An NVIS antenna configuration is a horizontally polarized (parallel
with the surface of the earth) radiating element that is from 1/20th
wavelength ... to 1/8th wavelength above the ground. That proximity to
the ground forces the majority of the radiation to go straight up.
Overall efficiency of the antenna can be increased by placing a ground
wire slightly longer than the antenna parallel to and directly
underneath the antenna. While the ground wire is not necessary under
good to excellent propagation conditions, antenna gain in the 3 dB to
6 dB range are common when the ground wire is used."

Since I've never heard of anyone doing this, or seen any hams trying it,
I'd like to hear from those who've done it, and find out if the gain is
as predicted.

73,

Bill W1AC, who is rushing to get a good sky-hook up before the winter

--
Bill Horne

(Remove QRM from my address for direct replies.)

Use of ground wires underneath dipoles
 

On Tue, 30 Sep 2008 18:39:02 EDT, Bill Horne wrote:

According to Wikipedia
(http://en.wikipedia.org/wiki/Near_Ve...dence_Skywave), a
horizontally-polarized NVIS antenna will benefit from a ground wire
underneath it.

Here's an excerpt:

"An NVIS antenna configuration is a horizontally polarized (parallel
with the surface of the earth) radiating element that is from 1/20th
wavelength ... to 1/8th wavelength above the ground. That proximity to
the ground forces the majority of the radiation to go straight up.
Overall efficiency of the antenna can be increased by placing a ground
wire slightly longer than the antenna parallel to and directly
underneath the antenna. While the ground wire is not necessary under
good to excellent propagation conditions, antenna gain in the 3 dB to
6 dB range are common when the ground wire is used."

Since I've never heard of anyone doing this, or seen any hams trying it,
I'd like to hear from those who've done it, and find out if the gain is
as predicted.

I have a chain-link fence along my property line. Maybe I can move my antenna
over to the property line and use the fence as ground wire.

73,

Bill W1AC, who is rushing to get a good sky-hook up before the winter

73, Dick, AC7EL in Southern Nevada, who is waiting for November or later to do
his antenna work. It was 95 degrees Fahrenheit today, still too hot for outdoor
work for this transplanted New Hampshirite. BTW, it almost never snows here.
73 de Dick, AC7EL

Use of ground wires underneath dipoles
 

"Bill Horne" wrote in message
t...
According to Wikipedia
(http://en.wikipedia.org/wiki/Near_Ve...dence_Skywave), a
horizontally-polarized NVIS antenna will benefit from a ground wire
underneath it.

Ever hear of a 2 element Yagi?

Use of ground wires underneath dipoles
 

In article ,
Bill Horne wrote:

According to Wikipedia
(http://en.wikipedia.org/wiki/Near_Ve...dence_Skywave), a
horizontally-polarized NVIS antenna will benefit from a ground wire
underneath it.

Here's an excerpt:

"An NVIS antenna configuration is a horizontally polarized (parallel
with the surface of the earth) radiating element that is from 1/20th
wavelength ... to 1/8th wavelength above the ground. That proximity to
the ground forces the majority of the radiation to go straight up.
Overall efficiency of the antenna can be increased by placing a ground
wire slightly longer than the antenna parallel to and directly
underneath the antenna. While the ground wire is not necessary under
good to excellent propagation conditions, antenna gain in the 3 dB to
6 dB range are common when the ground wire is used."

Since I've never heard of anyone doing this, or seen any hams trying it,
I'd like to hear from those who've done it, and find out if the gain is
as predicted.

73,

Bill W1AC, who is rushing to get a good sky-hook up before the winter

We used a configuration of that principal, for years, when doing
communications for the Ididarod DogSled Races out in the bush
of Alaska. Put up a Dipole for 80 Meters, strung between the trees,
and then ran a Grounded Wire, directly under the Dipole, that was 3%
longer, electrically. Increased our ERP for Short Range Comms.
Typical Ranges were from 120-500 Miles. KL7BB can give you any details,
you could require, if you can track Crazy Bill down......

Use of ground wires underneath dipoles
 

Dick Grady AC7EL wrote:

73, Dick, AC7EL in Southern Nevada, who is waiting for November or later to do
his antenna work. It was 95 degrees Fahrenheit today, still too hot for outdoor
work for this transplanted New Hampshirite. BTW, it almost never snows here.
73 de Dick, AC7EL


et tu, Brute?

--
Bill Horne

(Remove QRM from my address for direct replies.)

Use of ground wires underneath dipoles
 

You wrote:
In article ,
Bill Horne wrote:

According to Wikipedia
(http://en.wikipedia.org/wiki/Near_Ve...dence_Skywave), a
horizontally-polarized NVIS antenna will benefit from a ground wire
underneath it.
[snip]

Since I've never heard of anyone doing this, or seen any hams trying it,
I'd like to hear from those who've done it, and find out if the gain is
as predicted.

We used a configuration of that principal, for years, when doing
communications for the Ididarod DogSled Races out in the bush
of Alaska. Put up a Dipole for 80 Meters, strung between the trees,
and then ran a Grounded Wire, directly under the Dipole, that was 3%
longer, electrically. Increased our ERP for Short Range Comms.
Typical Ranges were from 120-500 Miles. KL7BB can give you any details,
you could require, if you can track Crazy Bill down......


What puzzles me is the ground: I don't understand why such a wire would
function as anything but, well, ground. I understand that it's a
parasitic reflector if not grounded (has anyone tried this?), but I
don't get the reason for the ground.

BTW, is it grounded at both ends?

73,

Bill W1AC


--
Bill Horne

(Remove QRM from my address for direct replies.)

Use of ground wires underneath dipoles
 

On Oct 2, 12:58 am, Bill Horne wrote:

What puzzles me is the ground: I don't understand why such a wire would
function as anything but, well, ground. I

I think it's really about ground (dirt) conductivity. Which varies all
over the place.

In some places (moist, loamy soil with lots of minerals, coastal areas
where the water table is very high and salty) the dirt is a pretty
good conductor, to the point where antennas "worked against ground" do
pretty well with just a ground rod or two. RF just bounces off that
sort of dirt.

In other places (dry, sandy, rocky soil) the dirt is a very lossy
counductor, and acts more as an RF absorber.

With a low dipole, the ground is so close that it has major effects on
the antenna. If it's lossy dirt, it just soaks up RF, but if it's a
decent conductor, it can act as a reflector. The added wire is just a
way of improving the ground conductivity in the dirt that is most
involved: the dirt directly under the antenna.

73 de Jim, N2EY

Use of ground wires underneath dipoles
 

Hi O,m's
interresting things around here about groundwires at a dipole
in my reply of the 3.5mc vertical i told that an antenna can bee seen as a
coil and a condensor
tuned at working frequencie
a run of wire has an inductance remind the stripline tuned circuit at vhf
if we have a normal tuned circuit coil and capacitance it is understandable
we see the parts
if the coil is a length of wire a litle less but if we remind uhf circuits
if we move the condensorplates to the top and bottom of the coil we can see
still the tuned circuit
and we have a new experimental antenna type google H antenna for more
details also commercial available
even precooked building instructions very interresting to understand the
basics of antennatheory
if we strech the coil we got the wireantenna where is the condensator hi
the wiresurface to earth
now we can understand that the dipole is a serial combination of two coils
and 2 condensators and a thirdth to earth
notice that there are 2 radiation paterns a magnetic from the coil and a
statthic from the condensator
so it is to understand that a groundwire under the dipole has an influance
at the capacity of the antenna and also at its radiation
the groundconditions of our garden chances rain moisture sun etc
the condition of the diged wire will not chance and the results of the
antenne too.
i hope i cleared a little
73 de ruud PA0RAB

schreef in bericht
...
On Oct 2, 12:58 am, Bill Horne wrote:

What puzzles me is the ground: I don't understand why such a wire would
function as anything but, well, ground. I

I think it's really about ground (dirt) conductivity. Which varies all
over the place.

In some places (moist, loamy soil with lots of minerals, coastal areas
where the water table is very high and salty) the dirt is a pretty
good conductor, to the point where antennas "worked against ground" do
pretty well with just a ground rod or two. RF just bounces off that
sort of dirt.

In other places (dry, sandy, rocky soil) the dirt is a very lossy
counductor, and acts more as an RF absorber.

With a low dipole, the ground is so close that it has major effects on
the antenna. If it's lossy dirt, it just soaks up RF, but if it's a
decent conductor, it can act as a reflector. The added wire is just a
way of improving the ground conductivity in the dirt that is most
involved: the dirt directly under the antenna.

73 de Jim, N2EY