Shack Grounding

[Handy Andy]

I am only going to put this in here and let you folks sort out the concept - because this has kept people that travel on the roads, alive due to the effect. Which is my presumption that we all can use a similar setup ourselves when it comes to RF and potentials we don't want floating around the shacks...



In my own experiences, a Faraday cage doesn't need to be a "Cage of mesh" only a rough conductive outline box using Pillars and beams that are tied off to ONE COMMON grounding point - outside the shack. - this way the RF currents are tied to one common exterior "shell" that stays confined within the box and also tied to the exterior tie off point to keep the RF currents from re-radiating to the exterior the box is located in - just to the grounding point..

I tend to show this common tie off as the ground located at the Antenna and use only single point power souring to help the user whom may have problems with Alternator whine as well as static noise pickup in his vehicle.

The mesh spacing only has to be closer than 1/4 wavelengths but can be of any length long to reach the tie off point.

Just some techniques I've used even at home to remove the RFI problems by mounting the Stereo and Computer within a similar perimeter of shielding shared by the Radio equipment so that all ties off are common to the same perimeter shield tie.

Just my thoughts on this...

 

[Shadetree Mechanic]

I think we're mostly on the same page. My opinion is that there should not be that much rf in your shack. What you say about the impedance transforming along the wire every 1/4 wave is true. The same is true for an antenna. If this is happening along that long ground wire it's likely radiating. It may provide a lower impedance path for rf than your tv, pc speakers or whatever but it's only eliminating the symptoms. The real problem is still there.

My main point is the long ground wire can radiate RF and pick up noise. With enough power that high voltage point in the center can burn you, arc to nearby cables and even start a fire. That's extreme but possible.

Ok I think I know what you are saying. If the ground wire is a half wave length, the ground wire will be radiating at the quarter wavelength point. You got me. I am going to have to think about how that works. Now you made me think! Haha!

 

[Dmans]

It is the number one never ending debate questions !

Are you sure that's #1?
Perfect Coax length? Perfect SWR? Perfect RMS/PEP ratio?


73
David

 

[Redbeard U812]

Are you sure that's #1?
Perfect Coax length? Perfect SWR? Perfect RMS/PEP ratio?


73
David

Forgot the super whack pac and swing mod......

 

[Shadetree Mechanic]

Ok I think I know what you are saying. If the ground wire is a half wave length, the ground wire will be radiating at the quarter wavelength point. You got me. I am going to have to think about how that works. Now you made me think! Haha!

Ok here it goes.....
When an antenna is radiating, the end of the antenna is at (and I am going to make up this term because I don't know what it is called) "Sky Potential" and the counterpoise is also floating in the air so it is also at "Sky Potential" because the antenna is in the air.

But the ground wire is different. The ground wire does not terminate in the air, it terminates to the earth.

If you look at a model of a quarter wave antenna, the impedance is high at the end and it radiates at the middle. So radiating and conducting are two different things. I am trying to explain something that was discovered 150 years ago. I have to go back to the first link that I posted to re read again. Because if I can't explain it, then I don't really understand it......

I apologize to the OP as this goes beyond answering the simple question you posted.

 

[Redbeard U812]

Shortest length is best for ground.

 

[Shadetree Mechanic]

Shortest length is best for ground.

Yes, except if the shortest length works out to be a quarter wave. Then you should make it a little longer or shorter. But its already the shortest length, so it has to go longer........

 

[543_Dallas]

Ok here it goes.....
When an antenna is radiating, the end of the antenna is at (and I am going to make up this term because I don't know what it is called) "Sky Potential" and the counterpoise is also floating in the air so it is also at "Sky Potential" because the antenna is in the air.

But the ground wire is different. The ground wire does not terminate in the air, it terminates to the earth.

If you look at a model of a quarter wave antenna, the impedance is high at the end and it radiates at the middle. So radiating and conducting are two different things. I am trying to explain something that was discovered 150 years ago. I have to go back to the first link that I posted to re read again. Because if I can't explain it, then I don't really understand it......

I apologize to the OP as this goes beyond answering the simple question you posted.

What about a loop antenna or a folded dipole?

 

[Handy Andy]

Ok here it goes.....

I apologize to the OP as this goes beyond answering the simple question you posted.

Since the post was July of 2019, No, you didn't go beyond...

There is a LOT to be said about Safety - which "Grounding" is simply a "satellite" branch of a many toothed cog all centered around You being Safe.

The poster wanted to know Grounding - and they got an earful, eyeful and Mindful amount of one simple premise - do not assume anything will stay out your shack when it comes to Mother Natures' whims - they only thing you can do to even remotely reduce that chance of the strike - is to never put up an antenna at all.

It's a challenge all of us face everyday - we live longer if we avoid taking risks. But some - like antennas, are unavoidable chances we take on, with providing the next to perfect complete path to ground - which may include us.

 

[Shadetree Mechanic]

What about a loop antenna or a folded dipole?

I don't know. I was just trying to explain the science behind it. Maybe it was not a good example.

The point I was trying to make is about the high impedance of a quarter wave ground. I didn't make this up. It was discovered 150 years ago. Information provided in the two links that I shared. Did you even look at them?

If we accept the antenna science, then what makes ground wire science so unbelievable?

Take it or leave it. I quit.

 

[Christopher17]

My 1/4 wave antenna is grounded with it's own wire to a copper rod just below the antenna, it's connected to the mounting lug where the radials and jacketed part of the coax meet, this was done so the antenna would work and have an acceptable SWR, Lighting? My rig is always unplugged when not in use, or when thunder storm is approaching ( both antenna and power supply) I am a human lightning rod and can tell stories about being struck and the damage incurred all afternoon, that's for another day , I don't get excited about connecting the radio chassis with it's own ground wire to the copper rod, (it's connected through the coax) I'm transmitting on fairly low wattage, chassis grounding may become more of an issue once I have more power

 

[543_Dallas]

I don't know. I was just trying to explain the science behind it. Maybe it was not a good example.

The point I was trying to make is about the high impedance of a quarter wave ground. I didn't make this up. It was discovered 150 years ago. Information provided in the two links that I shared. Did you even look at them?

If we accept the antenna science, then what makes ground wire science so unbelievable?

Take it or leave it. I quit.

I was just asking a question. I read the one article up to the point where he connected the ladder line to the "balanced output" of his transmatch. Then a little about the rfi problems one might have. I skimmed over the rest.

The guy doesn't know how to feed reactive load with the proper tuner. He knows the feedline is radiating due to an imbalance. Why didn't he just fix that problem? Been there.

You do what makes you happy and I will not question it.

 

[Flatop]

So im rf grounding the shack and lm aware that rf can resonate if the ground lead is of or near certain lengths. Id like to cover 10-11-12 meter range and from using a wavelength calculator I believe im safe with a 50' length. Am I correct?
My other question is what is better to use, 6 awg bare grounding wire or tinned/untinned strap and what width?

My understanding, the main thing is to avoid a quarter wavelength, or multiples thereof, with the ground wire at any of those operating frequencies.