Microwave source

Microwave only found applications into the 1940s and 1950s, much later than radio, because good enough sources were harder to develop.

One notable development was the cavity magnetron in 1940, which was the basis for the original radar systems of World War II.

Apparently, DC current comes in, and microwaves come out.

TODO: sample power efficiently of this conversion and output spectrum of this conversion on some cheap device we can buy today.