> The development of radar during World War II provided much of the microwave technology which made practical microwave communication links possible, particularly the klystron oscillator and techniques of designing parabolic antennas.
The fact that pre-war the links were a few dozen miles, vs transcontinental links post-war shows that it really wasn’t a viable technology before radar. And that’s generally true for most technology; war and the military tent to speed up the pace of technology development greatly.
The premise seems overstated to me...there's certainly some crossover, but both radar and microwave telephony were progressing in parallel.
>transcontinental links post-war
That would have to be relays. Even with tropo-scatter, microwave radios are only good for a few hundred miles. The "few dozen miles" limitation would just be the normal earth-curvature limitation that line-of-sight brings.
Looks like it, see what I've been reading:
> Work on klystrons became very intensive during WWII. Radar was independently invented in Germany and Britain before the war, and was initially implemented at UHF frequencies using triodes as sources. The invention of the klystron in the US encouraged the British in a search for a higher power microwave source, one which would make possible both better target discrimination and more compact transmitters. The 1941 invention of the magnetron by Randall and Boot in Britain16 provided such a source for radar transmitters. The same year, (and before Pearl Harbor) a visit by British scientists to America launched an extraordinary collaboration between Britain and the US, which resulted in magnetrons and klystrons being manufactured for the war effort in Western Electric, Sperry, and other American factories. The reflex version of the klystron, perfected at Sperry and in British laboratories, served as the local oscillator in superheterodyne radar receivers. Magnetrons powered the transmitters. Together, the magnetron and the klystron made possible airborne S-band radar, a major factor in securing air superiority for the RAF.
https://web.archive.org/web/20150924102609/http://www.slac.s...
> The klystron was the first significantly powerful source of radio waves in the microwave range; before its invention the only sources were the Barkhausen–Kurz tube and split-anode magnetron, which were limited to very low power. It was invented by the brothers Russell and Sigurd Varian at Stanford University. Their prototype was completed and demonstrated successfully on August 30, 1937.[5] Upon publication in 1939,[3] news of the klystron immediately influenced the work of US and UK researchers working on radar equipment.
- War effort requires a whole lot of capital investment -- factories built, equipment developed, people come up to speed, etc.
- Postwar, radar is still important, but the overall government expenditure falls.
- Much of the capital (manufacturing and expertise) searches for a peacetime use... and what's the low hanging fruit? Telecommunications.
That is, war money was being applied to both.