Radar, IMHO, stops England from being obliterated right out of the door. However, it’s MORE useful in that it allows Combined Arms to be purchased on the cheap (8 IPC, instead of 16-24 IPC).
As for the Atlantik Wall thing, I was thinking that Atlantik Wall represents all those fortifications the Germans built in Northern France, correct? Well they would provide SOME protection from shelling, hence why D-Day was not a stroll along the beach, but a bitter fight resulting in thousands dead before the first feet landed on the beach.
So why not have a national advantage impact a technology? Radar already impacts Jets by allowing them to be hit by AA Fire instead of being immune. So the precedent is already set on that score. And, to be honest, Atlantik Wall is a pretty good NA to have anyway. Free infantry a round in W. Europe and bonus on defensive dice from amphibious assaults AND a shot per round at your naval target of choice. (Even better when coupled with 88s.)
In fact, the more I think about it, the more I really like the idea. It’s not over powering. It would still take 6 infantry on the average to block one destroyer bombardment and it would have no impact on battleship bombardments. (12 inch guns vs 16 inch guns, I believe.) It’s pretty accurate in history since the area was fortified to high heaven. And, to top it all off, it does not require Germany to abandon W. Europe to stop the allies from, in essense, SBRing them to death with Destroyer/Battleship fire.
Meanwhile, it does cost the Germans for this protection, so it’s not like you are nerfing something the allies have. Germany is free NOT to take the NA (I’d maybe even recommend making it choice two and only after the allies have sunk a lot of money into Combined Arms and Destroyers. Just the threat of the NA could keep the allies honest.)