I've been doing a bit of reading and wonder about the following.

In a number of places I've read that in the case of a short vertical
antenna. the radials need be no longer than the height of the antenna
which in my case is about 8 ft. Even then I will be pressed to spread
out the currently planned eight 9ft. radials on my small balcony. I'll have
wire
all over the place but once I get things working I hope to lay a bit of
outdoor carpeting over the radials to make things look a little
neater.

No way will I be able to go 120 radials!! And there is no real practical
way of putting out off ground radials for each band!

The snow is still falling here!!! -- but I'm optimistic that by the
end of may I should be able to move things outside onto the
balcony and start playing.

Any comments or ideas will be welcome.

Irv VE6BP

Irv Finkleman wrote:
I've been doing a bit of reading and wonder about the following.

In a number of places I've read that in the case of a short vertical
antenna. the radials need be no longer than the height of the antenna
which in my case is about 8 ft. Even then I will be pressed to spread
out the currently planned eight 9ft. radials on my small balcony. I'll have
wire
all over the place but once I get things working I hope to lay a bit of
outdoor carpeting over the radials to make things look a little
neater.

No way will I be able to go 120 radials!! And there is no real practical
way of putting out off ground radials for each band!

For an elevated antenna, 3-4 radials are generally enough.

The 120 applies to radials on, in, or very very near the ground.


The snow is still falling here!!! -- but I'm optimistic that by the
end of may I should be able to move things outside onto the
balcony and start playing.

Any comments or ideas will be welcome.

Irv VE6BP






--
Jim Pennino

On 3/31/2014 10:38 PM, Irv Finkleman wrote:
I've been doing a bit of reading and wonder about the following.

In a number of places I've read that in the case of a short vertical
antenna. the radials need be no longer than the height of the antenna
which in my case is about 8 ft. Even then I will be pressed to spread
out the currently planned eight 9ft. radials on my small balcony. I'll have
wire
all over the place but once I get things working I hope to lay a bit of
outdoor carpeting over the radials to make things look a little
neater.

No way will I be able to go 120 radials!! And there is no real practical
way of putting out off ground radials for each band!

The snow is still falling here!!! -- but I'm optimistic that by the
end of may I should be able to move things outside onto the
balcony and start playing.

Any comments or ideas will be welcome.

Irv VE6BP



Florida is nice this time of year

Jerry, AI0K



--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

In article ,
"Irv Finkleman" wrote:

In a number of places I've read that in the case of a short vertical
antenna. the radials need be no longer than the height of the antenna
which in my case is about 8 ft. Even then I will be pressed to spread
out the currently planned eight 9ft. radials on my small balcony. I'll have
wire
all over the place but once I get things working I hope to lay a bit of
outdoor carpeting over the radials to make things look a little
neater.

Irv-

You do what you can. If you can tune the antenna for a match, you're on
the air!

In my experience, a short antenna such as a Hamstick does not work well
on 75 or 40 Meters using this method, especially with such short
radials. Adding radials may help, especially on the higher bands.

If you have a metal balcony rail, make a connection to the rail at the
base of the antenna, and run the radials from there. A clamp used with
a ground rod may work. Or you might use a trucker's CB mirror mount to
both make a ground connection and mount the antenna.

Example:
http://www.amazon.com/MIRROR-MOUNT-A...t/dp/B004X84B5
K

Fred
K4DII

El 01-04-14 4:38, Irv Finkleman escribió:
I've been doing a bit of reading and wonder about the following.

In a number of places I've read that in the case of a short vertical
antenna. the radials need be no longer than the height of the antenna
which in my case is about 8 ft. Even then I will be pressed to spread
out the currently planned eight 9ft. radials on my small balcony. I'll have
wire
all over the place but once I get things working I hope to lay a bit of
outdoor carpeting over the radials to make things look a little
neater.

No way will I be able to go 120 radials!!

Don't worry, it doesn't say that using less radials turns your antenna
into a dummy load. Just connect as much metal you can find together to
make a non-resonant ground provision.

Of course the overall antenna efficiency will be less compared to a
full size vertical with a solid floating or burried ground, but an
antenna with 10% radiation efficiency is always better then no antenna.

Don't forget to add some common mode provision (ferrite choke) where
the cable enters the shack.

Local interference may even be a bigger problem.

And there is no real practical
way of putting out off ground radials for each band!

The snow is still falling here!!! -- but I'm optimistic that by the
end of may I should be able to move things outside onto the
balcony and start playing.

Any comments or ideas will be welcome.

Irv VE6BP







--
Wim
PA3DJS
Please remove abc first in case of PM

Radials on a elevated antenna only works if the radials are placed at or near the bottom of the antenna and are arranged at a 45* angle.

Any other angle and you might as well not have any radials at all!

On a 10 -12 meter antenna, these radials would need to be at least 1/4 of a wavelength long - 9 feet and preferably 18 feet long to do any good!

If you coil them up they do not work as intended, but they might help a little.

Forget calling them a ground plane, think of them more like a mirror.

If you shine a beam of light directly at a mirror, the light is 100% reflected back towards the source.

If most of your radiated power is located at the bottom of the antenna and you can reflect that power up and forward - it is going to radiate better then something that is only partially effective.

Anything that you don't reflect is adsorbed into the ground - good for keeping the worms warm at night, but not good for radiating RF..

Only a fool would become a ham and then move into an apartment!

The sad truth is that most people do not understand what being a ham is all about anymore and most people thinks that amateur radio is a right and not a privilege.

Trying to be a ham while living in an apartment building would be like trying to be a Ocean liner captain while living in Oklahoma...

The metal railing is much too small in rf area to be an effective counter poise - sorry but who ever told you this should go back to school and get a real education.

El 01-04-14 19:21, Channel Jumper escribió:
Radials on a elevated antenna only works if the radials are placed at or
near the bottom of the antenna and are arranged at a 45* angle.

Any other angle and you might as well not have any radials at all!

I don't support this reasoning, I see many good antennas that don't
follow this rule.



On a 10 -12 meter antenna, these radials would need to be at least 1/4
of a wavelength long - 9 feet and preferably 18 feet long to do any
good!

If you coil them up they do not work as intended, but they might help a
little.

Forget calling them a ground plane, think of them more like a mirror.

I see the ground provision just as a means to pull out the current
that goes into the radiator (as I don't want to draw this current out
of the braid). If 1 A goes into the radiator, I need to draw 1 A from
my ground/counterpoise/etc. I would like to have the resistance of the
ground provision small with respect to the real part of the radiator's
impedance.


If you shine a beam of light directly at a mirror, the light is 100%
reflected back towards the source.

I think you can't compare the light analogy with a situation where the
wavelength is no long small compared to the structure.

A ground provision can be good enough for a well-designed half-wave
end-fed antenna, but useless for a quarter wave whip. You can't
explain this with light analogy.



If most of your radiated power is located at the bottom of the antenna
and you can reflect that power up and forward - it is going to radiate
better then something that is only partially effective.

Anything that you don't reflect is adsorbed into the ground - good for
keeping the worms warm at night, but not good for radiating RF..

Only a fool would become a ham and then move into an apartment!

Sometimes you don't have another choice and then you need to get the
best out of it.


The sad truth is that most people do not understand what being a ham is
all about anymore and most people thinks that amateur radio is a right
and not a privilege.

Trying to be a ham while living in an apartment building would be like
trying to be a Ocean liner captain while living in Oklahoma...

The metal railing is much too small in rf area to be an effective
counter poise - sorry but who ever told you this should go back to
school and get a real education.

It all depends on the current you need to draw from it, given certain
power. You will certainly not get good radiation efficiency, but this
doesn't say it is useless.

Given the good conditions at the upper end of HF, you can get useful
efficiency from a small antenna.


--
Wim
PA3DJS
Please remove abc first in case of PM

Channel Jumper wrote:

Radials on a elevated antenna only works if the radials are placed at or
near the bottom of the antenna and are arranged at a 45* angle.

Any other angle and you might as well not have any radials at all!

Utter nonsense.

The radials do have to be at or near the bottom but the angle of the radials
mostly determines the antenna impedance.

With the radials at 90 degrees the impedance will be around 40 Ohms and
at 45 degees very close to 50 Ohms.

One can download the demo version of EZNEC and observe the effect of
radial angle for themselves.

On a 10 -12 meter antenna, these radials would need to be at least 1/4
of a wavelength long - 9 feet and preferably 18 feet long to do any
good!

The ideal radial length for ANY ground plane antenna is slightly longer
than 1/4 wavelength, no matter for what frequencey.

If you coil them up they do not work as intended, but they might help a
little.

If you coil them up, you are inductively loading them, shortening the
physical length just like a loaded vertical.

If you make them electrically around 1/4 wavelength, loaded radials will work
just fine.

Ground plane antennas have been made with 4 hamsticks; 1 for the vertical
element and 3 for the radials and they work.

They major drawback to such is the limited bandwidth of loaded antennas.


snip remaining babbling nonsense



--
Jim Pennino

wrote:
Channel Jumper wrote:

Radials on a elevated antenna only works if the radials are placed at or
near the bottom of the antenna and are arranged at a 45* angle.

Any other angle and you might as well not have any radials at all!

Utter nonsense.

The radials do have to be at or near the bottom but the angle of the radials
mostly determines the antenna impedance.

With the radials at 90 degrees the impedance will be around 40 Ohms and
at 45 degees very close to 50 Ohms.

One can download the demo version of EZNEC and observe the effect of
radial angle for themselves.

On a 10 -12 meter antenna, these radials would need to be at least 1/4
of a wavelength long - 9 feet and preferably 18 feet long to do any
good!

The ideal radial length for ANY ground plane antenna is slightly longer
than 1/4 wavelength, no matter for what frequencey.

If you coil them up they do not work as intended, but they might help a
little.

If you coil them up, you are inductively loading them, shortening the
physical length just like a loaded vertical.

If you make them electrically around 1/4 wavelength, loaded radials will work
just fine.

Ground plane antennas have been made with 4 hamsticks; 1 for the vertical
element and 3 for the radials and they work.

They major drawback to such is the limited bandwidth of loaded antennas.


snip remaining babbling nonsense


Slight correction:

At 90 degrees the impedance will be close to 20 Ohms and at 30 degrees
close to 40 Ohms if not very close to the ground.

It would help if you were to specify what band or bands you are interested
in and how hight this balcony is off the ground.



--
Jim Pennino

El 01-04-14 21:33, escribió:
wrote:
Channel wrote:

Radials on a elevated antenna only works if the radials are placed at or
near the bottom of the antenna and are arranged at a 45* angle.

Any other angle and you might as well not have any radials at all!

Utter nonsense.

The radials do have to be at or near the bottom but the angle of the radials
mostly determines the antenna impedance.

With the radials at 90 degrees the impedance will be around 40 Ohms and
at 45 degees very close to 50 Ohms.

One can download the demo version of EZNEC and observe the effect of
radial angle for themselves.

On a 10 -12 meter antenna, these radials would need to be at least 1/4
of a wavelength long - 9 feet and preferably 18 feet long to do any
good!

The ideal radial length for ANY ground plane antenna is slightly longer
than 1/4 wavelength, no matter for what frequencey.

If you coil them up they do not work as intended, but they might help a
little.

If you coil them up, you are inductively loading them, shortening the
physical length just like a loaded vertical.

If you make them electrically around 1/4 wavelength, loaded radials will work
just fine.

Ground plane antennas have been made with 4 hamsticks; 1 for the vertical
element and 3 for the radials and they work.

They major drawback to such is the limited bandwidth of loaded antennas.


snip remaining babbling nonsense


Slight correction:

At 90 degrees the impedance will be close to 20 Ohms and at 30 degrees
close to 40 Ohms if not very close to the ground.

Jim, nice detail! Many reference say 35 Ohms (as they assume an
infinite ground plane), but it is really as low as you stated.

For JOTA oparation we used a 6 elevated radials arrangement at 40 m
band and I had to extend the radiator to get 50 Ohms. Just adding a
tuning capacitor "removed" the inductive component. Now we have the
means to erect a half wave giving sligtly lower main beam elevation,
and we use 3 radials now.


It would help if you were to specify what band or bands you are interested
in and how hight this balcony is off the ground.





--
Wim
PA3DJS
Please remove abc first in case of PM