Some results of researches and development of devices with field emission (TWT, BWO, carcinotrode, klystrons and X-ray tubes, field emission displays, etc.) have been briefly presented in the article. Lines of development of its theory have been designated. Also the vacuum microwave electronics programs offered in Europe and USA have been considered. They are directed on using new technologies in coping with the terahertz frequency range, reflecting the trend of recent years.
