Advantages of BWO, disadvantages of BWO, Backward Wave Oscillator
This page covers advantages and disadvantages of BWO (Backward Wave Oscillator). It mentions BWO advantages or benefits and BWO disadvantages or drawbacks. It provides links on various topics on BWOs.
What is BWO (Backward Wave Oscillator)?
There are two types of BWOs viz. O-type and M-type. The O-type BWO is used as low power oscillator with output in few hundred milli-watts over 1 to 15 GHz range. The M-type BWO is used to generate output in few hundred watts at GHz frequencies.
The working principle of BWO is similar to TWT. The figure-1 depicts diagram of BWO. As shown, O-type BWO uses elements such as electron gun, helix structure and collector plate. Electron gun is used to form and accelerate beam of electrons. Electron beam interacts with weak RF power to be amplified in the helix structure. Collector plate is used to collect electrons after the release of microwave energy. Refer BWO basics >>.
The O-type BWO is very useful as low power active device. It is also used as local oscillator or as low power modulator.
Benefits or advantages of BWO (Backward Wave Oscillator)
Following are the benefits or advantages of BWO (Backward Wave Oscillator):
➨In folded waveguide based BWO, output frequency of the BWO can be changed by varying the collector voltage. This is due to the fact that frequency of the BWO is controlled by transit time of electron beam as frequency band of given waveguide is usually constant. This transit time is controlled by collector potential.
➨As mentioned above, O-type BWO delivers output of few hundred milliwatts from 1 to 15 GHz while M-type BWO delivers output of few hundred watts in few GHz range. Hence either of this type can be used depending upon applications.
Drawbacks or disadvantages of BWO (Backward Wave Oscillator)
Following are the disadvantages of BWO (Backward Wave Oscillator):
➨The fixed spacing of folded waveguide used in the BWO design limits bandwidth of the BWO. This is applicable for BWO having folded transmission line between cathode and collector.
➨It delivers low efficiencies (about 20 to 30% ) compare to other microwave tubes such as TWT, Klystron etc.