I am starting a new thread because the old title about "worse SWR" and my 20ft vertical doesn't apply anymore. I decided to try a balloon (not balun on AM again. I did this experiment before some time last year, but it was before I understood the significance of large ground planes. This time the ground plane consisted of 32 30ft radials AND the huge metal roof on the building about 20ft away from the antenna (about 40ft x 20ft in size and 20ft above ground). Also this time I cut the antenna wire (20 gauge non insulated aluminum) to exactly 145ft long for 1700kc plus an extra foot for tying at the end. It's amazing how much better this works and how much easier it is than trying to build a vertical. You don't need a tuner or coils of any kind. The only downside is it's not permanent, but I intend to look for a better balloon that will hold its helium longer and also something with a bit more lift so I can use something like fishing line to lightly guy it so it doesn't blow around. The results were great. I got about a 6-7 mile clear range and 10 miles with tons of static using only 4W carrier. SWR was 1.08. I had to tweak it by wrapping the wire around a few times.
Now the obsession with AM starts again I plan to improve this setup by tying the base of the balloon wire on a small bracket part way up the wall of the metal roofed building and again, using the roof as a ground plane. I think with it mounted closer to the roof it should make it even better. I've also decided to put it on a certain corner of the building so that most of the metal roof will be in the direction I want the signal to go. I will also move my existing ground plane so that it covers the remaining 270 degrees around the corner of the building where I mount the antenna.
I have three questions about my plan. I can't easily have the wire start at the same height as the grounded roof. Is it OK to have it start about 10ft below the roof (ground plane)? It will also be about 8ft above the actual wire ground plane surrounding the corner of the building. Is that OK? Does the slant in the roof effect the signal?
on AM again. I did this experiment before some time last year, but it was before I understood the significance of large ground planes. This time the ground plane consisted of 32 30ft radials AND the huge metal roof on the building about 20ft away from the antenna (about 40ft x 20ft in size and 20ft above ground). Also this time I cut the antenna wire (20 gauge non insulated aluminum) to exactly 145ft long for 1700kc plus an extra foot for tying at the end. It's amazing how much better this works and how much easier it is than trying to build a vertical. You don't need a tuner or coils of any kind. The only downside is it's not permanent, but I intend to look for a better balloon that will hold its helium longer and also something with a bit more lift so I can use something like fishing line to lightly guy it so it doesn't blow around. The results were great. I got about a 6-7 mile clear range and 10 miles with tons of static using only 4W carrier. SWR was 1.08. I had to tweak it by wrapping the wire around a few times.