Ground radial question

[desync0]

I've decided I'm going to ground mount my (original 2 section) big stick, to 5 foot section of steel water pipe pounded in to the ground with about 18" sticking up.

But where I want to install it, my deck will block a portion of the ring of radials, will not having full 360 degree coverage make the antenna directional?

I bought a spool of 12g stranded and have some misc 12-14g stranded/solid core, so i should be able get 10-9' long radials with the 12g and a few 10-12' long from the random scrap wire, would that be enough?

 

[123kid]

In the past i did a deck mount and didnt have any problem hearing or transmiting to the east "which was blocked by my home.

 

[Justme]

Wood or stone won't "block" your transmitted signal, metal can effect the swr if it is too close or influence the radiated signal a bit, depending on how big the metal is, a few wires in the house a 10 feet away won't have a lot of influence or a metal pipe.

If it is aluminium siding then the story is different...

 

[desync0]

Vinyl siding on a wood framed house, so I should be ok there.

I was just worried that not having any radials, or only 1 or 2 on 1/4 of the circumference of the antenna would be bad.

 

[M0GVZ]

But where I want to install it, my deck will block a portion of the ring of radials, will not having full 360 degree coverage make the antenna directional?

I bought a spool of 12g stranded and have some misc 12-14g stranded/solid core, so i should be able get 10-9' long radials with the 12g and a few 10-12' long from the random scrap wire, would that be enough?

There is one site I read which claims around 3dBi down on the quadrant there are no radials. However this was not done on an antenna test range but merely by personal observation.

Put out what you can, where you can, as long as you can. Many short ones are better than a few long ones.

 

[W5LZ]

You can't have too many radial but you can certainly not have enough. An antenna will work with a few radial but will work much better with a lot of them. The same thing goes for safety ground radials too, the more the merrier.
The pattern you lay radials in does affect the radiation pattern of that antenna. If the radial field is symmetrical then the radiation pattern is also going to be 'sort of' directional too. Other things around the antenna affect it's being directional and how much so. I think I'd describe it as more of 'lop-sided' than very directional in most cases. It's usually not worth worrying about.
- 'Doc

 

[BJ radionut]

Doc: Do you remember the "original" Big Stick antenna?
Was it not a Vertical Bazzoka...ie: coaxial sleeve feed dipole?

Are you really going to "gain"anything by adding radials to the bottom of the terminated sleeve???

Only reason I ask is I tried that like 30+ years ago on one of those old sticks and never was able to say adding the radials hooked to the mounting sleeve made a "Hill of Beans" difference...

Your the man that's why I am asking....

CK: Any Thoughts from you OM?
"And they're off"....op:
Extinguisher ready!

All the Best
Gary

 

[Marconi]

Doc: Do you remember the "original" Big Stick antenna?
Was it not a Vertical Bazzoka...ie: coaxial sleeve feed dipole?

Are you really going to "gain"anything by adding radials to the bottom of the terminated sleeve???

Only reason I ask is I tried that like 30+ years ago on one of those old sticks and never was able to say adding the radials hooked to the mounting sleeve made a "Hill of Beans" difference...

Your the man that's why I am asking....

CK: Any Thoughts from you OM?
"And they're off"....op:
Extinguisher ready!

All the Best
Gary

I agree Gary, I can't be for sure, but I too think the old Big Stick was a 1/2 wave sleeved dipole, sort of on the order as the current day Gain Master's balanced feed point design, thus radials are not necessary.

I don't think radials hurt however, and if you place a large field of copper in or on the ground below such an antenna...it can't hurt. I really doubt, however, that you'll be able to detect a difference just using your radio, except maybe in your imagination.

IMO, removing a radial sure isn't going to make your vertical directional either, at least to a point that you can really tell just using your radio.

 

[desync0]

Thanks for the input guys, I've already got the wire so like you said it can't hurt, maybe they'll save a few earthworms from cancer? lol

When I tried it just bunjied to my deck I had no problem making a local contact on ssb, but with conditions the way they where yesterday I have no way of telling if adding the radials would make a difference in long range propagation.

I also ended up moving the antenna more equidistant from the fence and the deck, the corner of the deck was too close to the power/cable/phone lines for comfort.

 

[Captain Kilowatt]

Gary, I too am sure the original bigstick was a coaxial sleeve halfwave. If it is ground mounted it would beefit from radials a bit. At least to reduce ground losses. Not having some insome areas won"t make it noticeably directional at all. I wouldn't worry about laying out a mile of wire but just lay out what you can where you can.

 

[W5LZ]

"Are you really going to "gain"anything by adding radials to the bottom of the terminated sleeve???"

No, you won't be 'gaining' anything if you are considering it to be making the antenna -it's self- more efficient. But you will be affecting it's performance by increasing how it interacts with the 'dirt' (ground) under it.
The ends of an 1/2 wave antenna are high voltage points. And since the feed line is 'exiting' that 'end' of the 1/2 wave, it's going to be subjected to that high voltage, which can and does place currents on the outer shield of that feed line (those nasty CMCs, right?). So, one method of getting rid of those CMCs is to provide them a path lower in 'resistance' than that feed line. If there are enough ground radials then the 'resistance' presented to those CMCs by the radials is less than the 'resistance' offered by the feed line. If you were the CMCs, which would you take?
- 'Doc

(Is that a 'scientifically' accurate way of describing what happens? No, but it's a 'simpler' way of thinking about it, picturing it.)

 

[jazzsinger]

So, one method of getting rid of those CMCs is to provide them a path lower in 'resistance' than that feed line.)

surely in a sleeve dipole that lower path would be the bottom half of the antenna/outside of the shield depending if construction is a metal sleeve or purely coaxial, to get rid of common mode current add a choke/line isolator at the point where the cable exits, not the true feedpoint which is in the middle like most other dipole's.

which is exactly what Sirio did with the gainmaster. i don't see them adding ground radials, or advising it should be ground mounted either for that matter. If you want to minimise ground effects the solution is obvious, move it further from the ground, same as you would if any other conductor was causing issues due to closeness.

 

[W5LZ]

Putting an antenna higher can certainly reduce the affects caused by a 'dirt' ground. If you can move the antenna higher, some can't, or want it ground mounted for whatever reason.
A coaxial choke certainly works too, probably the only reason why they were made/used. But they aren't the only solution to CMCs, just like a good radial system isn't the only solution either. More than one way of doing that sort of thingy, the 'best' method is the one that is possible and that works for you.
- 'Doc

 

[BJ radionut]

"Are you really going to "gain"anything by adding radials to the bottom of the terminated sleeve???"

No, you won't be 'gaining' anything if you are considering it to be making the antenna -it's self- more efficient. But you will be affecting it's performance by increasing how it interacts with the 'dirt' (ground) under it.
The ends of an 1/2 wave antenna are high voltage points. And since the feed line is 'exiting' that 'end' of the 1/2 wave, it's going to be subjected to that high voltage, which can and does place currents on the outer shield of that feed line (those nasty CMCs, right?). So, one method of getting rid of those CMCs is to provide them a path lower in 'resistance' than that feed line. If there are enough ground radials then the 'resistance' presented to those CMCs by the radials is less than the 'resistance' offered by the feed line. If you were the CMCs, which would you take?
- 'Doc

(Is that a 'scientifically' accurate way of describing what happens? No, but it's a 'simpler' way of thinking about it, picturing it.)

Doc: Won't degree a bit. I never would discourage anyone from not doing something to improve (reduce ground looses) their system and did not intend for it to translate in that order.
However having been through that era when myths abound about this antenna or that one....
The "Radials" on the BigStick and the "old" Ringo designs were the chatter...
I would love to grade this whole almost 2 acres yard down.
Then blanket the whole thing in brass "chicken wire"....add few inches of top soil...
I could think of a few antennas I would try with that "ground mat" in place...
All the Best
Gary

 

[northern35s]

I just ran a quick simulation of a ground mounted dipole over real ground and over perfect ground, the difference is stark, however I believe the difference takes place in the far field, not the near field, so the addition of radials around the base of the antenna will probably have little affect on the radiation pattern, maybe this is a project for someone with a little more skill in antenna modelling to have a go at