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Ground plane over Quad
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Hmmm . . . . Don't think I would use a ground plane above ANY Yagi or Quad beam.
The ground plane itself will certainly react with the polar pattern of either beam - unless there is considerable distance between them. Quarter wave/9 ft or more. I would have no problem with putting a Imax or A99 above a Yagi. But not above a Quad.
The ground plane itself will certainly react with the polar pattern of either beam - unless there is considerable distance between them. Quarter wave/9 ft or more. I would have no problem with putting a Imax or A99 above a Yagi. But not above a Quad.
Robb why you contradicting yourself in the same post?
An Imax is a ground plane so is the A99 they do not need ground radials.
I agree any ground plane that requires ground radials I would not put above a yagi, and no type of ground plane above a quad, if you go to all the effort to build and install a quad at height, why put another antenna in it's radiation pattern to hinder the performance of the quad by skewing the pattern.
Didn't contradict myself. "Project" wasn't specific about which ground plane antenna. Had he said an Imax or A99; my post would have reflected that thought. When someone thinks of a real 'ground plane' antenna, I would think it is more like a Maco V5/8 - something with metal radials below.
Yes the Imax/A99 are a ground plane antenna; but I wouldn't use the radial kits on them if putting it above a Yagi. The Yagi itself will act as ground plane radials. Integrating without major conflicts in the radiation pattern of either.
Thanks for bringing it up, waverider.
I have the IMAX 2000 above my Mosley PRO67B, just like ROBB stated. of course the Pro is horizontal and the IMAX is 10 feet above the yagi, I see no ill effects using either antenna.
Any two (or more) antennas near each other will affect each other. "Near" means within several wave lengths. How detrimental is that affect? It can amount to not being able to tell any difference to very noticeable, either in a good way or a bad way.
If those two antennas are resonant on the same 'band', then there will be more affect than if they were for bands further in frequency from each other (HF and UHF, for example). But there will still be some affect.
It isn't going to make a huge difference what kind or style of antenna those two are, they will 'know' there's another antenna near them so their behaviors will change. That's completely normal.
The positioning can make a difference, where they are in relation to each other. Putting an antenna over (or under) another antenna tends to 'regularize' the changes in the radiation patterns of both antennas. That can mean that while there's some affect, it isn't noticeable (vertical over a directional antenna). Moving those two antennas so that they are 'beside' each other can make a very large difference, both detrimentally and beneficially in particular instances.
So how do you thell if it's going to be worth doing? By finding out what happened when others have done the same thing, or by being very good at antenna modeling, or by trying it and seeing for yourself.
Positioning an omni-directional antenna over a quad is more difficult than over a yagi type antenna. Why? It's a mechanical thing, as in how are you going to separate them? It'll mean a longer mast to get the thing above the quad than it would over a yagi. Nothing says you can't do it, but it's not going to be as easy. The idea is whether it'll be worth the effort to you, or not.
How do you tell before hand? Beats me! Just depends on what it's worth to you.
- 'Doc
If those two antennas are resonant on the same 'band', then there will be more affect than if they were for bands further in frequency from each other (HF and UHF, for example). But there will still be some affect.
It isn't going to make a huge difference what kind or style of antenna those two are, they will 'know' there's another antenna near them so their behaviors will change. That's completely normal.
The positioning can make a difference, where they are in relation to each other. Putting an antenna over (or under) another antenna tends to 'regularize' the changes in the radiation patterns of both antennas. That can mean that while there's some affect, it isn't noticeable (vertical over a directional antenna). Moving those two antennas so that they are 'beside' each other can make a very large difference, both detrimentally and beneficially in particular instances.
So how do you thell if it's going to be worth doing? By finding out what happened when others have done the same thing, or by being very good at antenna modeling, or by trying it and seeing for yourself.
Positioning an omni-directional antenna over a quad is more difficult than over a yagi type antenna. Why? It's a mechanical thing, as in how are you going to separate them? It'll mean a longer mast to get the thing above the quad than it would over a yagi. Nothing says you can't do it, but it's not going to be as easy. The idea is whether it'll be worth the effort to you, or not.
How do you tell before hand? Beats me! Just depends on what it's worth to you.
- 'Doc
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