For as long as I can remember, almost all older sims take a pretty basic approach to radar. Hills and mountains be damned, if you fly behind a hill - the game will still see you (even though there is a million and half tonne of impenetrable rock between you and the radar system.
All new games, including DCS, radar works as it should - you can hide behind tall structures, hills, inside valleys, and mountains - SAM's and radars be blind.
Aces High prides itself in realism, and most of us enjoy that fact. Fuel and WEP management, wind, haze, clouds, and including our complicated damage model. The in-game radar system, however, is left with a 1999 design. There is no reason then, that given the primitive radars of WWII, should a tower or sector radar be able to spot an enemy fighter if they're behind a mountain or tall hills.
I would also like to add, that while field radar are a powerful strategic importance to field defence, taking out enemy radar is a tactic to employ when attempting to capture an enemy field.
Why can't we do the same for sector radar? Shouldn't sector radar's facilities be destroyable? In WWII, they're usually identifiable as tall flat metal grids that are usually unidirectional. Like these german and british units:



Every map should have these all along the coast or behind the front lines scanning for incoming aircraft (or ships if along the coast).
And they should be destroyable (and repairable via supplies).
So, is it time we update the radar units to make it more realistic? Give gameplay new strategies and tactics to use against? Make mountains and hills radar proof?