Vacuum electronics in India

The vacuum electronic era started with the invention of vacuum diode by JA Fleming in 1904. However, the foundation of microwaves was laid in India much earlier by one of the fathers of radio science Acharya Jagdish Chandra Bose in 1890's in Calcutta. He used waveguides, horn antenna, dielectric lenses, polarizer's and even semiconductor detector, while working at the 2.5 cm to 5 mm wavelength. Today, the vacuum electronic devices (VEDs) are an essential component of many defense, space, and high energy research and civilian systems employing rf, microwaves, or x-rays or simply high speed switching. Defense systems like Radar, electronic warfare, communication and missile systems; high energy particle accelerators, TeV colliders, fusion reactors, industrial and domestic-ovens, medical imaging, hyperthermia, high power electric transmission etc. all require VEDs. Presently, India is one among just a dozen countries in the world having the ecosystem of academia, research laboratories production enterprises and a significant domestic market in defense, space, civilian, high energy research and ISM sectors to nurture innovation in these devices.