Total posts : 45366
I wonder if your window frame setup you described previously doesn’t accomplish the same thing as a 4″ copper pipe.
Ermi explained in a previous post the effect of diameter on bandwidth and I hope it was not lost on the readers here that factors other than antenna diameter in a practical part 15 AM antenna system dominate the antenna diameter. I wouldn’t use anything beyond about a 3/4 inch pipe and that is primarily for mechanical considerations.
I recall a principle which says “You spend 80% effort for 20% gain”. Even if true I think the percentages are way off when dealing with part 15 antennas. More like 99% effort for 1% gain once you get past a certain point.
It seems that the most effective things one can do is use a loading coil and install ground radials and put the vertical antenna outside. Beyond this there appears to me to be no legal means to increase coverage.