Originally Posted by microtony
Height makes little difference for ADS-B since it is ground-to-air (other than clearing obstructions).
Very true. However, over here in Africa we do tend to have rather large and high trees, thus one needs have an antenna at least 10meters/30feet above ground. Doing that very experiment of height / range at present, and with an antenna that's 6m above ground, I barely get 180km range with a 3.5 element coco. Where my 8 element coco on 14m AGL gets +-400km. My problem lies not with high buildings, but with trees and topography.

I would not mind having access to that nice mast over there in Cotonou..... !