I just noticed in my previous post, I said it would be about 4" from the back, I meant it would be about 4cm from the back. Anyways, here is some pictures of my pringles antenna. I found that the pringles can wasnt sufficiently strong enough to hold the longer reflector stable, so i used some plexiglass pieces to make for easy holding, and stability. Worked well, but it didnt do very well in the rain, got soggy and now the probe moves around some (very bad thing) I don't really use it much anymore, the cans are definately better. Also is another picture of my pineapple antenna with collector. (the collector isnt as bent looking as the picture seems to show, its just a trick with the light on the mesh)
http://www.forgottenfords.org/pringles1.jpg
http://www.forgottenfords.org/pringles2.jpg
http://www.forgottenfords.org/collect2.jpg