Microwave and Millimeter Wave Vacuum Electron Devices Top US$1 Billion Again

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By Lance Wilson | 1Q 2019 | IN-5369

For 2018, the market has remained strong.

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Historical Perspective


Microwave and millimeter wave Vacuum Electron Devices (VED), or vacuum tubes, as they are also known, are one of the last links to the dawn of the electronic era in the early and mid-twentieth century. While using basic vacuum tube principles, complex internal geometries and adjacent magnetic fields are also at play in these types of VEDs.

These devices can either be amplifiers or oscillators and are capable of generating extremely high-power RF that can reach to the multi-megawatt range. Without going into too much detail, there are five basic microwave and millimeter wave VEDs that comprise the modern marketplace. They are:

  • Travelling Wave Tubes (TWT)
  • Klystrons
  • Magnetrons
  • Crossed-Field Amplifiers (CFA)
  • Gyrotrons

Actual operation of these tubes can be quite involved and, while some may consider them an anachronism to a bygone era, they are actually multi-disciplinary in both design and manufacture. The technologies are wide-ranging and include precision machining, glass/metal and ceramic/metal seals, high-vacuum technology, rare-earth metallic components, metal plating, high-technology welding and brazing, cathode/heater development, heat exchanger sub-systems, and other electromechanical methodologies. When looked at in total, these technologies and skills all point to modern technology in execution.

Today's Marketplace


The biggest modern influence in the market has most certainly been the introduction of gallium nitride (GaN) RF power semiconductor devices as a competitive force. GaN can work to and beyond 50 GHz. This technology is in play today, and GaN has been capturing some share of the VED market.

At one time a few years ago, the conventional wisdom was that GaN RF power semiconductors would eventually replace microwave and millimeter wave VEDs. This never happened and currently the VED market is stable with a very slight amount of growth. Further, there are many very high-power applications where the cost of using GaN would be prohibitive.

This scenario has evolved into a stability of sorts from a business perspective, with GaN replacing some helix TWTs and being introduced into new applications where appropriate. In a similar fashion, microwave and millimeter wave VEDs have portions of the overall market that are more suited to that technology. Overall, this VED market was more than US$1 billion in 2017.

The result is that market positioning and essential device functions and attributes have become more clearly defined between the two technologies. This is likely to be the marketplace characteristic for the next decade or so at a minimum.

Moving Forward


There is still confusion within the RF semiconductor community about why there is not more microwave and millimeter wave business and why the “replacement” of VEDs has been so slow. This is the most common lack of understanding in the microwave and millimeter wave VED business.

With this in mind, ABI Research has some very specific recommendations that vendors, especially RF power semiconductor suppliers, need to heed. ABI Research has brought up some of these points previously, but they still have not resonated with the semi side of things. It is important that, at a minimum, they are at least understood.

  • VED vendors understand the GaN marketplace a great deal better than the semiconductor vendors understand the VED business. The net result has been surprise, some confusion, and disillusionment with the lack of apparent microwave and millimeter wave opportunities.
  • GaN vendors need to set realistic expectations and time frames on GaN intrusion into the microwave and millimeter wave market. This is driven home to a certain extent by the previous point but, nevertheless and despite previous warnings, the expectations have almost always been overly optimistic.
  • One needs to realize that the VED business will still be with us for many years.
  • The world’s current trade and tariff issues will slow things down, but in the long term, they will be worked out.

This subject matter is discussed fully in ABI Research’s new market data, MD-MMTU-18, and report on the same topic, AN-4913.