Regarding antennas, what does counterpoise mean?

[Marconi]

I for one appreciate the input. It is a use of the word that I have not heard before.


The DB

I always thought a discone was basically a receiving antenna.

Wire Dawg did you tell us where you said the counterpoise was on this antenna? If not, can you point to the counterpoise or describe where it is? If it was a transmitter type, can you show us a picture and also show us the counterpoise. We're trying to determine in this thread what a counterpoise might look like and maybe you could help.

 

[Marconi]

All of your points are well taken.

All of my mobiles to date are verticals where the model you used had a inverted L wire.

Again, this model with the inverted L wire was the only image I've found that indiacted it was representative of an antenna with a counterpoise...and it was noted to be a very old image.

As for your model going over like a lead balloon, I have looked it over several times and this is referenced to it. There have not been too many comments in general on any models posted except the CST models, and Eznec as it relates to those. Most of us don't know what we're looking at, I think.

I wasn't talking about my models in total, I was referring to the models I posted for this counterpoise issue. I've been trying to explain as best I can what and how I see modeling. I don't fully understand modeling either, but a lot of what I see looks pretty simple. However, I have to consider my modeling could all be a waste of time and space to post on these forums.

It would still be nice to see how a vertical model compared to other antenna types.

If you're talking about a straight 1/4 wave radiator instead of the inverted L look, here it is, both at 27.205 and 1.85 mhz. It looks like a little better gain and a little better angle that the flat top antenna.

View attachment The Classic counterpoise idea with a full .25 wave radiator.pdf

While I may be willing to give a nod to the possibility of AM broadcast stations having used a horizontal wire with counterpoise, I do not believe it was limited in those days to such usage or else the early writings on the subject by Ham operators are meaningless.

Here is an old one I found, but whether they were horizontal or vertical was not the point of my comment. I was trying to relate the fact that the Classic Counterpoise image had a horizontal radiator of sorts.

Here is a link so you can read the text to the image. San Francisco Radio

You can sorta' make out the counterpoise wires on the poles all around the site.

 

[HomerBB]

Thanks, Marconi. I understand.

Some of the images produced on the thread for this discussion show the counterpoise as a circular networks with the what I would assume is the vertical in the center.
Cool old photo.
It looks to me that if that raised network of wires beyond the suspended antenna are the counterpoise for this system the station was trying to create a largely directional effect like your models show. So by saying you are at this point leaning toward VK10D's perspective you are saying it is a counterpoise when it acts as a director?

He says it is only a counterpoise when it influences gain in the far field, which coupled with your model results would indicate some kind of directing capability.

 

[The DB]

Marconi, I'm not going to say for a second that that diagram you used is wrong, but most diagrams and explanations I have come across show a 1/4 wave vertical (sometimes shortened in the case of LF antennas) over a spiderweb layout of wires or some sort of mesh screen.


The DB

 

[Marconi]

Marconi, I'm not going to say for a second that that diagram you used is wrong, but most diagrams and explanations I have come across show a 1/4 wave vertical (sometimes shortened in the case of LF antennas) over a spiderweb layout of wires or some sort of mesh screen.


The DB

Well, since we don't have a good idea of what was used back when guys talked about the counterpoise in the 20s, the only thing we might do is look for old pictures like this.

If you go to the image and click on home page, you will find a history of a sorts. There are lots of names and locations that can also be referenced and maybe lead us to a gold mine of information about the antennas of the day.

As we already know our antenna of our day come in may shapes and sizes, so me might expect that is more or less what was going on back then too.

 

[Wire Dawg]

Marconi: Sorry but I do not have pictures of these antennas. The website for the Ground Electronics Engineering & Installation Agency (geeia.org) used to have a couple of pictures, but I was unable to find them. The section that we used to refer to as the counterpoise was right smack in the middle of the whole structure (apex). There was a certain value that was sought by lowering the curtain of wires before the antenna could be accepted/ released for use. I will try to find my old tech manuals to obtain a side view of the discone.

 

[Marconi]

Thanks, Marconi. I understand.

Some of the images produced on the thread for this discussion show the counterpoise as a circular networks with the what I would assume is the vertical in the center.

I also take it as the vertical is in the center. Those images that DB posted sure do look like what we might consider as a counterpoise, the one at the top shows the word in the image and looks like a spider web. If I ever saw that image before I probably would have referred to it as a counterpoise. This would probably include the other shapes as well.

Cool old photo.

It looks to me that if that raised network of wires beyond the suspended antenna are the counterpoise for this system the station was trying to create a largely directional effect like your models show. So by saying you are at this point leaning toward VK10D's perspective you are saying it is a counterpoise when it acts as a director?

No homer, I think the counterpoise wire network in that photo was centered and under the antenna. The text of the article where the image was found said the same. That is why I posted the link.

I don't think the counter poise is a directional feature, but in both of my Eznec models, using the 3 wires positioned a little above ground, that is what we see, a skewed directional pattern. I also see the same when I made the inverted L with a full 1/4 wave vertical radiator, and the three wire counterpoise as noted. The three radials, in this case, look to amplify the L pattern and the effect is gain.

He says it is only a counterpoise when it influences gain in the far field, which coupled with your model results would indicate some kind of directing capability.

Homer, excepting that both men discussed the counterpoise, there is no connection that I know of between VK1OD and this image or the man that made it.

I used this image as a demonstration for what modeling might say about the design. At the time I wasn't even aware of VK1OD. I assure you that before I did the model I could only guess at what the pattern looked like. That is why I did the model, I wanted to know what Eznec might indicate.

Maybe VK1OD was thinking as you suggest, but I didn't think that was what he meant when he presented the definition. He gave several ideas, but I don't recall his conclusions at the moment, except to say the word is probably best left out of discussions. I would have to read it again.

This who said what business is getting confusing for me...when it may be hours between my reading posts.

Have you considered to try a shot at this counterpoise idea? Keep up the good work.

 

[HomerBB]

I just wondered out loud about whether your saying you leaned toward an explanation VK10D had offered may have been partially due to the offset model you had done. I didn't have any notion that VK10D had seen the picture.

I don't know why I did not see the antenna in the photo you provided centered over the lower network when I looked at it the first two times. . .

I will try the raised counterpoise soon I think.

 

[Marconi]

I just wondered out loud about whether your saying you leaned toward an explanation VK10D had offered may have been partially due to the offset model you had done. I didn't have any notion that VK10D had seen the picture.

I don't know why I did not see the antenna in the photo you provided centered over the lower network when I looked at it the first two times. . .

I will try the raised counterpoise soon I think.

Try this link: The Radio Historian

This article is also noted a #2 in the address for the link, so there may have been more than one antennas over time. Look in the section captioned as Power Station.

In the text it describes how the antenna was positioned, but it says the wires are parallel to the antenna, and I see them as running perpendicular. I can't explain that difference, but maybe the article is saying the counterpoise field of wires is parallel to the antenna since the field is likely longer than it is wide.

I'll check further and see if I can find another image that shows the site better.

 

[Marconi]

Here is KGO today and they've gone vertical with three towers I think.

KGO Today

Here is another old radio station antenna on top of a building.

San Francisco Radio

 

[W5LZ]

"In the text it describes how the antenna was positioned, but it says the wires are parallel to the antenna, and I see them as running perpendicular."
I think you may be seeing the supports for those parallel wires. The 'wires' being run over those supports.
- 'Doc

 

[Marconi]

"In the text it describes how the antenna was positioned, but it says the wires are parallel to the antenna, and I see them as running perpendicular."
I think you may be seeing the supports for those parallel wires. The 'wires' being run over those supports.
- 'Doc

That could be 'Doc.

 

[The DB]

Marconi's picture is a new idea of a counterpoise for me. It is the fist older example I have seen of a counterpoise being used with a strictly horizontal antenna.

Unfortunately it is difficult to pick out some needed details to piece it all together. They did say 12 parallel wires, yet I see only 5 posts on the right side of the tower supporting the counterpoise, where are the other 7 needed posts on that side as each of the 12 parallel wires would need support. Even if some of them were behind us you should still see more than 5 posts for the parallel wires within the frame

Good find Marconi, but unfortunately I think it raises more questions than it answers for me, which isn't necessarily a bad thing...


The DB

 

[Marconi]

Here is the best example of early broadcast antennas I've found: History of KFWI

 

[HomerBB]

More than likely the twelve parallel wires are an additional eight across the four as a criss-cross network. There would be no need of more posts.