Is the radio only being placable on solid ground intentional? I know it says you can't place it in front of platforms, but I doubt that means you can't place it on them. Unless it does?
Yes, the radio must be grounded. This is for the dual purpose of forcing more mindful placement for the end game objective and also preventing the frustrating situation of a very expensive building collapsing from one platform below getting destroyed.
Nice. Time to figure out how to get a good spot for the radio. Alas, I also already have that expensive building collapsing pain from just normal playing.