Isolate and 0.125 CP for 1/2 wave 10m ?

[FreshLogan]

8 meters of pole, would you isolate a basic cb end fed coil loaded 1/2 wave antenna for 10 and 11m and add a small copper wire counterpoise or just direct
bolt to the pole ?

As this is voltage fed I imagine the risk of CMC is small on the pole.

I find counterpoise such as odd concept to understand.

I could isolate bracket from pole and add a copper wire on a bolt 0.125 wavelength long instead if it made the pattern better.

On one hand we know that it allows cmc to flow somewhere but does that cmc affect radiation pattern. And if so I imagine it depends on its phase and if it even radiates from the pole or counterpoise or not.

I read radials do not radiate so maybe CP does not radiate either and maybe the pole neither. So why do we need a CP in the first place ?

CP's / poles / isolating or not is as clear as mud to me.

Thanks

 

[BayouRadioAmplifier]

I have my old A-99 mounted to a five-foot mast with the
coax going at a right angle to my house and radio room.
I will put it back on a taller mast again.
Works great on "27 MHz CB" 29.000 MHz AM and 29.600 MHz FM.

the mast / radials / CP are the other half of the antenna.
the antenna just looks "end-fed"

But mounting it on that 8-meter pole will make for a good
omni directional antenna.

I have a friend that has RF problems with an A-99 antenna
and has a 1 to 1 unun to help isolate the coax shield from carrying
some RF. Maybe he is running his coax down his metal mast. ??

RU-1:1 Unun

www.ldgelectronics.com

.....

 

[Henry HPSD]

Although still under construction..but maybe it gives a couple hints:

Mast and coax influence on a vertical antenna – 19DX348 CB Antennas

cb-antennas.com

At the bottom of the page youll find an end-fed halve wave at 8.25m with antenna plots and current.

I still need to do quite some work on that page,
(Hope to do that upcomming weeks) but it will give you an idea.

Ps although the pattern doesnt change that much you have to keep in mind the additional issues (noises etc).

Kind regards,
Henry

 

[FreshLogan]

Thanks for those Henry. It seems I will just ensure this metal mast is not grounded as I do not have a non conducting mast. I can isolate the silver rod from the mast (removing a DC short to its bracket - A basic Sirio GPS 1/2 ) but the mast is still conducting, being aluminium.

It seems to be working ok as it is which is basically non grounded. I just up and down the mast as needed it is not up permanently.

I wired brushed the SO-239 outside and in a little as it is looked lacking in shine, looked very cloudy, that will ensure a better coaxial contact.