Basics of Microwave Tubes
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Basics of Microwave Tubes book
Before the microwave energy is transmitted, radiated, propagated or processed to achieve the desired goal, it has to be generated and amplified. At the dawn of the electronic era, this task was carried out by vacuum tubes. In view of the explosion of knowledge, the use of higher frequencies became a necessity. As the frequency range was enhanced, it was noticed that these conventional (vacuum) tubes utterly fail to yield the desired results beyond certain limits. In the quest to overcome these limitations, a new class of tubes, referred to as microwave tubes, emerged. Before discussing the construction, principles of operation and other aspects of microwave tubes, it is necessary to understand the following aspects:
1. Causes of failure of the conventional tubes at higher frequencies 2. Behaviour of charged particles in the presence of different fields
since the working of all the tubes, particularly those used at microwave range, is based on the movement of electrons
3. Concept of velocity modulation, a key phenomenon in almost all microwave tubes
In the following sections, these three aspects that can be termed as basics of microwave tubes are discussed. Finally, the classification of microwave tubes is also included.