Just thinking about the importance of sector airfields in the Battle of Britain, perhaps putting say, 5k of eggs on the dar or tower of the zone base should take out dar on all country fields within that zone, or, all such fields except the one you are currently at [simulating the knocking out of the coordinating function of a zone/sector airfield].
OTOH, knocking out hq means that you can't see what shows on dar in other sectors, but still can see dar returns from your own sector [assuming zone dar for that sector is still up].