Microwave tubes are all too easily now considered part of historical exhibits at trade shows. But according to a new report from ABI Research, "Microwave and Millimeter Wave High-Power Vacuum Electron Devices and the Gallium Nitride Threat," this market is far from history. In fact, the report notes that the total available market (TAM) for microwave and millimeter-wave high-power vacuum tubes is almost $1 billion. Although these electron devices are vital to many applications, the market is often misunderstood and inaccurately reported.

For many applications, especially at higher frequencies, tubes provide power levels that cannot be achieved except by large numbers of combined transistors. Particularly at millimeter-wave frequencies, tubes are often the only way to generate significant output-power levels. The industry supporting electron tubes has admittedly gone through changes and consolidation in recent years as designers have sought solid-state solutions for applications once powered by tubes, but the industry is fairly stable now. The ABI Research report points out GaN devices as possible replacements for some tubes, but many may remember that the same claims were made for gallium arsenide (GaAs) transistors more than 20 years ago. Time will tell, of course, but it would appear that the need for electron tubes is still strong and likely will remain so for some time.