how far does rf ground go ??

[BOOTY MONSTER]

an antenna will use what ever it can find for rf ground , coax , mast , ground wire . say someone grounds their antenna to a waterpipe (bad idead i know but it happens) or the ground rod for the buildings electrical system . is that antenna also grounded to every other plumbing pipe in the city (assuming no rubber/plastic sections) or the electrical wiring in every house and everyone elses antenna connected to those places at their residences ? i dont think so ......... but im asking if anyone really knows . does it just disapate shortly after it has adaquate contact with good ol mother earth/dirt ?

how far will the ground go befor its no longer affected to what its connected to ?

 

[Marconi]

As stated in your post, I'm not one that would claim to really know, but I ask you--- what is your real question? I think you have something on your mind besides physically how far your RF goes when it comes in contact with some conductive element attached to an earth ground on your property like you describe.

Ask yourself what happens when mega volts of lightning strikes something conductive like you describe? How far do you think that current goes towards your neighbors? Relative to the power involved with lightning strikes how do you think your puny little RF power will react under similar conditions?

Have you ever heard or read discussions on the misuse of the words "ground, ground plane, counterpoise, and maybe a few others terms," relative to the antennas we talk about? These discussion are usually dealing with confusion due to terms ideas.

I think I found the real issue BM. Is it to be found in the article by K0BG on ground losses you posted elsewhere?

 

[BOOTY MONSTER]

just trying to learn more about how antennas work and how different things affect them and how other things dont or arnt worth considering .

on the lightning strike im thinking (but im probally really thoughtin') that it travels at the speed of light and with immense power but the electrical resistance in wire/pipe/tubing and its current capicaty causes it to explode frome the heat befor the resistance allows it to go very far . thats purely a guess . if im anywhere near correct is a whole other thing !! lol

im just full of questions ..... im sure some others would suggest something else too . hahaha

tks M

 

[Marconi]

I just added this to my original post, but you beat me back to the thread.

I think I found the real issue BM. Is it to be found in the article by K0BG on ground losses you posted elsewhere?

 

[BOOTY MONSTER]

actually i didnt link them together in my head . the article youre refering to is about mobile antennas but my question here was about base antennas . i do go back to Ks' to read and re-read his articles though . but i do that several other places too . usually when i go back later and read it again ill catch things that i didnt befor .
but , anyhow . no , i wasnt gathering ammo . lol .

 

[Marconi]

If information is not ammo, then it is worthless. Why do you want to know how far does rf ground go?

 

[Cajun Invader]

A properly installed, connected and balanced antenna would never need an RF station ground. All the current flowing out of the antenna would be equally matched by current flowing back on a second conductor like a shield or some sort of balanced line.

The issue here is that most antennas are built poorly or the coax is not up to par. So what we get now is a common mode current.

So with that said the best course of action would be to spread the RF out from your antenna feed point into a large area with the use of radials. What this does is create an electrical mass for your antenna to push out against.

People often confuse the different types of grounding.

Lightning Grounding is mainly for equipment safety and not that good for RF grounding. Lightning grounding requires an earth contact to move energy into our lossy soil as where RF Grounding may be shielding our frequency from the earth or even moving our RF energy out of the lossy soil or minimizing the RF ground into the lossy soil.

RF Energy in our lossy soil mainly happens when an antenna is too close to earth for it's wavelength.

The answer to your question is simple. I don't really know.

 

[dudmuck]

how far will the ground go befor its no longer affected to what its connected to ?

If its really earth ground, then the earth will dissipate some of the energy given too it.

I am thinking what you're really talking about is the counterpoise.
Think of a swimmer diving off the diving board. The diving board is his counterpoise.
If the swimmer has nothing to push against, then he wont jump effectively.
Diving boards have a certain flex or stiffness, that is your equivalent to impedance.
The diving board passes some of the swimmers energy to what its mounted on.
How far does that bounce travel back into the earth? Its the same question that you ask.


Cajun Invader: there is also another reason to ground. To lower your receive noise floor by preventing static buildup on your tower/antenna. Up your font size up a notch, you're doing wonders for my eyesight.

 

[Cajun Invader]

Cajun Invader: Up your font size up a notch, you're doing wonders for my eyesight.

A properly installed, connected and balanced antenna would never need an RF station ground. All the current flowing out of the antenna would be equally matched by current flowing back on a second conductor like a shield or some sort of balanced line.

The issue here is that most antennas are built poorly or the coax is not up to par. So what we get now is a common mode current.

So with that said the best course of action would be to spread the RF out from your antenna feed point into a large area with the use of radials. What this does is create an electrical mass for your antenna to push out against.

People often confuse the different types of grounding.

Lightning Grounding is mainly for equipment safety and not that good for RF grounding. Lightning grounding requires an earth contact to move energy into our lossy soil as where RF Grounding may be shielding our frequency from the earth or even moving our RF energy out of the lossy soil or minimizing the RF ground into the lossy soil.

RF Energy in our lossy soil mainly happens when an antenna is too close to earth for it's wavelength.

The answer to your question is simple. I don't really know.

 

[W5LZ]

Booty M',
RF is just like other electricity (sort of), it's going to go as far as it can until it's dissipated. And like any electron, it get's stopped by things that don't conduct. Okay, so how far is that? That depends on how conductive the thingy is. Dirt isn't very conductive and the distance traveled will be less than for a good conductor like metal. All that's 'normally' required to dissipate an RF signal is something on the order of about a 1/4 wave length. That's is you're talking about a groundplane, counterpoise, whatever. It's far enough to 'work'. If those radials (whatever) are longer, you'll find some current at the end of them too. How much current depends on the stren gth of the original signal and how much resistive losses there are. Great huge gobs of "fudge factor" room in that! Also why apartment building wiring, fences, water pipes can cause as much problems as they 'cure' in grounding.
So if you're looking for a definite, "it never gets any further than this" kind of number, you are out of luck.
All of this radio stuff is so -exacting-, ain't it??
- 'Doc

 

[C2]

how far will the ground go befor its no longer affected to what its connected to ?

I think that you will find that the "ground" will not be affected by what it's connected to after 1 wavelength.

 

[BOOTY MONSTER]

thanks guys . it just seems that antennas are affected by many things that adjust their performance and dispersion pattern . i guess im just wanting to be sure that if i ground a base antenna that i knew what (if any) other differences it might make in its pattern . im thinking that if i have a proper ground radial setup on the antenna (like a maco5/8 or starduster type antenna) that it wouldnt matter anyway .