Ground plane radial clearance to objects?

[N2MRG]

I can be more specific if it would help, but for a ground plane radial to be effective, how much clearance (from other objects) should these radials have on all sides?

For example if I mount an antenna as pictured below... these is some limited distance between the ground radial and the roof of my dwelling. Obviously it would be ideal if the antenna were located at the peak of the roof, but this is not possible. Is there a rule of thumb for how far away it should be otherwise?

 

[n8zcc]

This can become rather complex depending of the use of the antenna. What frequency is the antenna cut for? Is the antenna going to be used to transmit. If you answer yes to the second and the antenna is for 6 meters and lower frequencies then I suggest getting a copy of the antenna book from the ARRL.

If you are going to use it for receiving on VHF and above, a 1/2 wave length distance is a good rule of thumb. You can get closer than that assuming there is no conductive materials in the roof.

 

[LtDoc]

Would it work? I'm sure it would, wouldn't make a guess on how 'well' it would work though. Will the radials (actually the whole antenna) be affected by how close something was to it? Sure, unless the thing's mounted a mile away from everything a jillian feet in the air. Most of the time, that 'affected' thingy isn't all that much of a biggy, it can be compensated for as in it's tuning. Don't be too concerned about getting it absolutely 'right', that almost never happens anyway. (I'd leave out that "almost" part, but sometimes it happens, miracles do happen occasionally.)
distances with antennas get's a little 'odd'. It's usually measured in wave lengths, not inches or feet. The greater the distance away from stuff, the better. But you have to 'temper' that with what's practical! I'd love to have all my antennas several wave lengths away from stuff but that's just not going to happen. So, you make the best of whatever you have to work with. Sometimes that isn't too good, but you won't have a choice.
A very, -very- rough way of figuring this sort of thingy is that things should be at least the length of the antenna away from anything else. Try it, see what happens. Wanna see if moving it just a little this way/that way helps? Do so. There are no 'universal' best answers...
- 'Doc

 

[TheSpaceMan]

The best advice I can give is to get it as high as possible, even if you need to mount it on the side of your home. I once built a 2 Meter ground plane and mounted it on my deck right next to the edge of my house. I got it up on 20 feet of mast, and it worked wonderfully!