On Fri, 09 Mar 2012 09:58:45 -0600, dave wrote:

On Thu, 08 Mar 2012 12:35:58 -0600, NM5K wrote:

On 3/8/2012 11:09 AM, dave wrote:
On Thu, 08 Mar 2012 08:51:20 -0600, NM5K wrote:

Also, ground mounted verticals will still need radials if the antenna
is to live up to it's expectations. And there is nothing to stop one
from using one elevated, if one uses resonant radials for each band
to be used.

My GAP Titan DX requires no radials; it is a center fed, asymmetric
vertical dipole.


Well, ground mounted monopoles in his case.. Being a "complete"
antenna, it's true that the center fed vertical does not require
radials for proper operation, but you would still likely show lower
ground losses if it were over radials. For instance, broadcast stations
that use 1/2 wave radiators still use a set of radials under the
antenna. Usually 1/2 wave radials, when used with a 1/2 wave radiator.
You will still see some ground loss with the ground mounted 1/2 waves
over poor ground, but being as the max current point is 1/4 up from the
ground, it's not near as severe as the ground mounted 1/4 wave where
maximum current is at the base.

I don't think a ground screen is needed if you are 1/2 wave.

If you elevate a short vertical you only need a few "ground" radials
(think CB groundplane antenna), btw. My whole transmit antenna system
floats on my roof. The only "ground" is the panel where the RF goes
through the wall. I receive on a balanced 30m horizontal loop, also
floating except for the point of entry. I have an automatic tuner at the
feedpoint under the eave by my kitchen window. (FWIW) I have lived here
14 years and have never seen lightning at the shack.

WABC on the rocks

http://www.musicradio77.com/transm.html

On Fri, 09 Mar 2012 10:00:10 -0600, dave wrote:

On Fri, 09 Mar 2012 09:58:45 -0600, dave wrote:

On Thu, 08 Mar 2012 12:35:58 -0600, NM5K wrote:

On 3/8/2012 11:09 AM, dave wrote:
On Thu, 08 Mar 2012 08:51:20 -0600, NM5K wrote:

Also, ground mounted verticals will still need radials if the
antenna is to live up to it's expectations. And there is nothing to
stop one from using one elevated, if one uses resonant radials for
each band to be used.

My GAP Titan DX requires no radials; it is a center fed, asymmetric
vertical dipole.


Well, ground mounted monopoles in his case.. Being a "complete"
antenna, it's true that the center fed vertical does not require
radials for proper operation, but you would still likely show lower
ground losses if it were over radials. For instance, broadcast
stations that use 1/2 wave radiators still use a set of radials under
the antenna. Usually 1/2 wave radials, when used with a 1/2 wave
radiator. You will still see some ground loss with the ground mounted
1/2 waves over poor ground, but being as the max current point is 1/4
up from the ground, it's not near as severe as the ground mounted 1/4
wave where maximum current is at the base.

I don't think a ground screen is needed if you are 1/2 wave.

If you elevate a short vertical you only need a few "ground" radials
(think CB groundplane antenna), btw. My whole transmit antenna system
floats on my roof. The only "ground" is the panel where the RF goes
through the wall. I receive on a balanced 30m horizontal loop, also
floating except for the point of entry. I have an automatic tuner at
the feedpoint under the eave by my kitchen window. (FWIW) I have lived
here 14 years and have never seen lightning at the shack.

WABC on the rocks

http://www.musicradio77.com/transm.html

Bird's Eye View: http://www.bing.com/maps/default.aspx?
v=2&cp=40.880654933621~-74.069307757843&style=a&lvl=15&sp=Point.40.8806549 33621_

On 3/9/2012 9:58 AM, dave wrote:


I don't think a ground screen is needed if you are 1/2 wave.

It's not required to provide the lower half of the antenna, but
they will still reduce ground losses if the antenna is ground mounted.



If you elevate a short vertical you only need a few "ground" radials
(think CB groundplane antenna), btw. My whole transmit antenna system
floats on my roof. The only "ground" is the panel where the RF goes
through the wall. I receive on a balanced 30m horizontal loop, also
floating except for the point of entry. I have an automatic tuner at the
feedpoint under the eave by my kitchen window. (FWIW) I have lived here
14 years and have never seen lightning at the shack.

The number of elevated radials needed to equal certain number on
the ground will depend on the wavelength above ground.
IE: to equal 120 1/4 WL radials on the ground, at 1/8 WL, you will need
appx 60 of them. At 1/4 WL, appx 8-10.. At 1/2 WL, 3-4..
And if the radiator is short, the radial system is a bit more
critical than with a full size 1/4 wave radiator.

On 3/9/2012 10:13 AM, dave wrote:


WABC on the rocks

http://www.musicradio77.com/transm.html

I bet their halfwave is sitting on a bed of 1/2 WL radials.
Most 1/2 wave BC antennas tend to use 1/2 wave radials I'm fairly sure.
Part of this is due to FCC requirements for stability in performance,
etc..
A 1/2 WL radiator on the ground is not immune to ground losses.
It just suffers less than the 1/4 WL.
And a 1/2 wave elevated, really should be decoupled from the feed line
for best performance. Of course, it's not required, but they will
perform better if you use decoupling. Less skewing of the pattern
off the horizon, from feed line currents.

Found it

Actually, I found some very old schematics , the paper is yellowish tea
like. Japanese I think . Hidaka.

http://www.hidaka.com/e-a_multi-v.html#VS-41W

I am pretty sure the one I have now is the VS-80KR.

I am going to clean it up and try it out. Don't know what will happen when I
put it on a 50 ft tower in these windy days. Will have to calculate the
length of gnd planes. I suspect they will be too long.

Any recommendations?

Thanks

73




"NM5K" wrote in message
...
On 3/9/2012 9:58 AM, dave wrote:


I don't think a ground screen is needed if you are 1/2 wave.

It's not required to provide the lower half of the antenna, but
they will still reduce ground losses if the antenna is ground mounted.



If you elevate a short vertical you only need a few "ground" radials
(think CB groundplane antenna), btw. My whole transmit antenna system
floats on my roof. The only "ground" is the panel where the RF goes
through the wall. I receive on a balanced 30m horizontal loop, also
floating except for the point of entry. I have an automatic tuner at the
feedpoint under the eave by my kitchen window. (FWIW) I have lived here
14 years and have never seen lightning at the shack.

The number of elevated radials needed to equal certain number on
the ground will depend on the wavelength above ground.
IE: to equal 120 1/4 WL radials on the ground, at 1/8 WL, you will need
appx 60 of them. At 1/4 WL, appx 8-10.. At 1/2 WL, 3-4..
And if the radiator is short, the radial system is a bit more
critical than with a full size 1/4 wave radiator.

On 3/9/2012 3:09 PM, Tuuk wrote:
Found it

Actually, I found some very old schematics , the paper is yellowish tea
like. Japanese I think . Hidaka.

http://www.hidaka.com/e-a_multi-v.html#VS-41W

I am pretty sure the one I have now is the VS-80KR.

I am going to clean it up and try it out. Don't know what will happen
when I put it on a 50 ft tower in these windy days. Will have to
calculate the length of gnd planes. I suspect they will be too long.

Any recommendations?

Not really, as the antenna in the picture seems to use
loaded/trapped radials. So you will need their assembly
specs if you have those and plan to use them.
Or maybe assemble them and try to tune them.
If elevated, any full size wire radials will need to be resonant.
If ground mounted, there is no need to tune radials laying on or in
the ground.

I don't have the ground planes for this antenna, just the vertical main
mast.

Used on the ground would be difficult because I am sandwiched between houses
all around me.

I wonder would the mismatch be so significant that the efficientcy of the
antenna be almost completely lost? If used with a good tuner would the
radiation resistence of the antenna become totally innefficient if I were to
completely ground it out through the tower? Nice idea having a omni all hf
band antenna. I run barefoot anyway.

I think I will try it out anyway, I have one of those MFJ old manual tuners
and am sure it would match the feedline coax with the antenna to the load.
Just curious how efficient the antenna would radiate. Being 50 foot above
the ground, approx 500 ft above sea level anyway. I think the deciding
factor is that there is nothing on top of the tower now anyway.

Thanks

73





"NM5K" wrote in message
...
On 3/9/2012 3:09 PM, Tuuk wrote:
Found it

Actually, I found some very old schematics , the paper is yellowish tea
like. Japanese I think . Hidaka.

http://www.hidaka.com/e-a_multi-v.html#VS-41W

I am pretty sure the one I have now is the VS-80KR.

I am going to clean it up and try it out. Don't know what will happen
when I put it on a 50 ft tower in these windy days. Will have to
calculate the length of gnd planes. I suspect they will be too long.

Any recommendations?

Not really, as the antenna in the picture seems to use
loaded/trapped radials. So you will need their assembly
specs if you have those and plan to use them.
Or maybe assemble them and try to tune them.
If elevated, any full size wire radials will need to be resonant.
If ground mounted, there is no need to tune radials laying on or in
the ground.

On 3/10/2012 8:21 PM, Tuuk wrote:
I don't have the ground planes for this antenna, just the vertical main
mast.

Used on the ground would be difficult because I am sandwiched between
houses all around me.

I wonder would the mismatch be so significant that the efficientcy of
the antenna be almost completely lost? If used with a good tuner would
the radiation resistence of the antenna become totally innefficient if I
were to completely ground it out through the tower? Nice idea having a
omni all hf band antenna. I run barefoot anyway.

I think I will try it out anyway, I have one of those MFJ old manual
tuners and am sure it would match the feedline coax with the antenna to
the load. Just curious how efficient the antenna would radiate. Being 50
foot above the ground, approx 500 ft above sea level anyway. I think the
deciding factor is that there is nothing on top of the tower now anyway.


No telling how it will tune. If you use no radials, the whole
structure will be acting as the antenna. Radiator, and tower.
Results could be all over the map depending on the band. It would
be better to have at least one resonant elevated radial per band to be
used.

Thanks for the information.
I think it is very top heavy, and up on a 50ft tower will just wait for a
good wind to bring it down.

While I see no ground plane brackets with this, there is no way to put gnd
planes at each section.

Haven't done nothing yet, maybe wont. Maybe will.

Thanks for the information.

73s





"NM5K" wrote in message
...
On 3/10/2012 8:21 PM, Tuuk wrote:
I don't have the ground planes for this antenna, just the vertical main
mast.

Used on the ground would be difficult because I am sandwiched between
houses all around me.

I wonder would the mismatch be so significant that the efficientcy of
the antenna be almost completely lost? If used with a good tuner would
the radiation resistence of the antenna become totally innefficient if I
were to completely ground it out through the tower? Nice idea having a
omni all hf band antenna. I run barefoot anyway.

I think I will try it out anyway, I have one of those MFJ old manual
tuners and am sure it would match the feedline coax with the antenna to
the load. Just curious how efficient the antenna would radiate. Being 50
foot above the ground, approx 500 ft above sea level anyway. I think the
deciding factor is that there is nothing on top of the tower now anyway.


No telling how it will tune. If you use no radials, the whole
structure will be acting as the antenna. Radiator, and tower.
Results could be all over the map depending on the band. It would
be better to have at least one resonant elevated radial per band to be
used.