Thank You for Your input. I've made the changes You've suggested (or at least tried to), but I'll wait a bit with posting the drawing, as perhaps there will be more suggestions.
Thiel - it's rather something like 60-65 degrees, but I get Your point.
WhyMe - I've made the radar platform 3 pixels thick, though I'd say it looks bit odd now. I tried to add some details too, though on the other hand it's a small drawing and there isn't too much space for it.