Deleted member 1487
No and the cavity magnetron had nothing to do with the VT fuse. A big problem there was Hitler ordered halt of defensive weaponry not ready in 6 months in 1940 to get ready for Barbarossa and didn't restart proximity fuse research until 1942 sometime. So they lost about 2 year and had a ridiculous number of versions with all sorts of triggers (acoustic, infrared, etc.). By the end of the war they were getting one ready for production based on an electro-static principle, but the war situation, conscription of scientists since 1940 and on all delayed the project so it never was ready. Likely best case scenario it could have been ready in 1942-43 without the 1940 halt order to research and no conscription of scientists and fewer projects and concentration of resources.Is 1935 early enough to have radar proximity fuses in service for 1940? AFAIK the Luftwaffe's flak arm was so large even then that it might be possible to get the cost reductions that the Americans achieved later in the war.
But the Proximity Fuse was a minor component to high altitude bomber killing. Accurate radar and gunnery computers, servo-motors slaved to the radar and gunnery computer, and auto-fuse setter were much more important when working as a system. As I said both the Germans and US were getting ~300 rounds average per bomber kill in 1944-45 with 9-10cm radar without proximity fuses. The US did get down to about 100 rounds per V-1 kill with proximity fuse, but the other components were more important to improving shoot down rates. The Germans averaging 300 rounds per bomber kill would be 10x more effective on average than they were in their best year of bomber killing in 1942. Window reduced accuracy to abysmal rates in 1943-45, but 9cm radar was able to penetrate cloud of aluminum foil.
Perhaps it would increase KM gunnery accuracy; certainly in night actions it would be very helpful. Yes naval and regular AAA would be very much improved with 10cm wave length or less radar guidance. The 1941-1942 attacks on German warships would suffer very badly as a result.I wasn't thinking in terms of the Germans having more surface warships, but it might give the ones they had an advantage over the Royal Navy before they caught up. For example in night actions such as the destroyer attack on the Bismarck, Hipper's encounter with a British troop convoy and some of the Russian Convoy battles.
Would better AA gunnery radar either with or without proximity fuses have helped the Bismarck when she was attacked by torpedo bombers from Victorious and Ark Royal? IIRC a combination of the Mk 37 director and VT fuses helped the South Dakota shoot down 20 Japanese aircraft at the Battle of Santa Cruz.