Total posts : 45366
If you consider what I mentioned earlier, two blocks home range sounds good.
The sudden drop is probably due to moving from the near field (1/r^3 reduction) to the far field (1/r reduction). I forget the exact details, but I bet Rich could elaborate on this.
Regarding power lines, I transmit from an antenna in my basement since I am just using my system for personal stuff around the yard. My neighborhood has underground utilities and only my neighbor and I are on the same distribution transformer. Though I do not intentionally couple to the power lines and probably would not get through the transformer if I did, I do notice when I do a mobile check that if I am under a pole power line I can hear my signal about two miles away. The line is probably acting as a receive ant. in this case, but it does make one wonder if the lines could be legally exploited.