More than a half century later, traveling-wave-tube amplifiers still dominate satellite communication. That's right—your ultrahigh-definition satellite TV and satellite radio come to you courtesy of vacuum tubes in space.
Of course, there's a huge difference between Telstar's 3.5-watt, 4-gigahertz amplifier and one of the dozens of highly efficient microwave amplifiers on, say, the DirecTV-15 satellite, launched earlier this year. The latest generation of traveling-wave tubes can provide up to 180 W at frequencies up to 22 GHz, with efficiencies approaching 70 percent and rated lifetimes exceeding 15 years. Though their basic function is the same—amplifying RF signals—just about everything else has changed: the design, the testing, the materials, and the fabrication.
...
And now, ongoing research into a new and potentially revolutionary kind of traveling-wave tube—the ultracompact and ultraefficient cold-cathode TWT—looks poised to deliver the first practical device by the end of this decade. These are exciting times for vacuum tubes. Here's why.
No cheating this time--read the article to find out why.
(Score: 0) by Anonymous Coward on Friday November 27 2015, @09:50PM
"digital" singles [...] analog single
I'll take 5 of each please.
s/single/signal
-- gewg_