Those problems to the south and west are 30 miles away, the east problem is almost 50. It all depends on the altitude of the planes in those areas. You may not have normal flight routes in those empty areas?
I am right next to the Little Rock VOR, so most of the flights I see are heading directly to or away from me. There are others of course, but they mostly seem to be flying a route across the north part of the state.
What I dont understand about SBSPlotter, is I can watch a plane on the map flying across the south part of the state, at 130 miles, but on SBSPlotter, it doesnt aways show up. That area is blank, even though I just watched a plane fly across that area.
The east problem you say is at 50 miles, would probably be Crowleys Ridge, which rises from the flatlands at Mississippi river height, to over 450', and run the entire length of the state from north to south. Its about 50 or 60 miles away.
To the south, there is nothing that stands out, height wise at any distance, and to the west of course, are all mountains, some are in the 1100' range and pretty much cover the whole state from WSW to NW of me.
With the new antenna, I can see the planes pop up and drop off to the east, just as they fly over that ridge, so that makes sense. The other directions with nulls are probably just terrain. Im guessing I have about all the range I can get right now, short of finding a really low noise preamp to mount up at the antenna, and I doubt that would gain me much more. I do plan on raising the antenna another 10' to try to clear some trees in the yard, sometime soon. Just wanted to make sure I had enough coax to do that.