[agere_contra]

The cavity magnetron was key to the British radar chain that put the RAF one step ahead of the Luftwaffe in the Battle of Britain. Anti-aircraft batteries slaved to radar, radar on ships for tracking surface ships and submarine periscopes - all unbelievably important.

Someone once said that Radar stopped Britain losing the war (along with the huge Navy and the English Channel, of course).

[ASOC]

The Chain Home radar was HF - closer to OTHR (Over the Horizion Backscatter Radar) than the newer microwave systems in use later in the war. OTHR is making a comeback with the new high power computers in use today.

Back in the day, the SovBlcok had the "woodpecker" radar and we had a ROTHR system where the HAARP system sits today.

From http://www.radarpages.co.uk/mob/ch/chainhome.htm

For all its faults (HF technology, poor low level cover below 2o, slow data transmission and so on) the CH flood-light radar system represented the best general early warning system that could then have been devised given the technological capability and the level of scientific knowledge available in Great Britain at that time. CH held the fort until new technologies such as the cavity magnetron developed by Messers Randall and Boot could be brought into service use.