2.2.3 Examples of application of a magnetron with two energy outputs

The vistas of developing the magnetrons associated with stabilization of frequency and improvement of its frequency characteristics including its operation in the multifrequency mode and the electronic frequency tuning [21, 35, 36, 38].

A block diagram of a device on basis of the magnetron with two RF energy outputs and realizing a multifrequency mode of an operation with electronic tuning of a frequency from pulse to pulse is shown in Figure 14.

As may be seen, the given block diagram of the pulsed magnetron generator includes a magnetron with two RF outputs: active – 1 and passive – 2, as well as modulator – 4, which is synchronized with a pulsed power supply 7 for commutation of the p-i-n diodes D1 and D2 of an electronic switch 5. The microwave energy generated a magnetron, on the one hand, is consumed by a matched load 2 via the active RF output 1 and on the other hand is passed the reactive RF output 3 and entered on a microwave switch 5. The microwave switch is a device, which has one input and several outputs each has a load in short-circuit waveguide form length of

#### Figure 13.

3D images of a classical magnetron design (a) 1—an anode block; 2—a matching transformer; 3—a RF output of energy and a magnetron with two RF output of energy (b) 1—an anode block; 2—a matching transformer of an active RF output; 3—an active RF output of energy; 4—a matching transformer of an reactive RF output; 5—an active RF outputs of energy.

Vacuum Microwave Sources of Electromagnetic Radiation DOI: http://dx.doi.org/10.5772/intechopen.83734

Figure 14.

A block diagram of the multifrequency magnetron generator [21, 38].

Li, where i ¼ 1, 2, 3, … N (in our case, N ¼ 2). In the process, a value of N defines a number of frequencies generated by the magnetron, generally.

In recent years, there is a major interest in the creation of the high power microwave tubes and the electronic systems on its basis [9, 15, 16, 29, 33, 42]. An analysis shows that for getting the high power microwave radiation, there are several possible approaches based on:


The vistas of creating the high-power microwave electronics are associated with developing the high-power relativistic microwave tubes, which are provided by generation of high-power microwave pulses (peak power is units and tens GW) [9, 33]. However, the application of such devices is connected with considerable technical and technological difficulties, especially, when need to produce a compact microwave electronic system generating very short microwave pulses (duration less 100 ns). In this case for forming high power microwave pulses, there are simpler approaches based on application both the high-voltage Marx's generator and the nonrelativistic microwave tubes (magnetrons). In the last case, we supported to apply the pulse compression technology, namely the resonant microwave compression method. A central idea of this method is slow storage of electromagnetic energy in the microwave resonator and then its removal from the high factor resonator for shorter duration to a matched load (antenna) [42]. Among advantages of this method, it is necessary to note its ease of its realization, the possibility of application the industrial magnetrons, as well as the standard elements of waveguide techniques. In our case, we consider an operation of the microwave module, in which the magnetron having the two RF outputs of energy is used.

#### Figure 15.

Block diagram of the high power microwave module [43]. 1—a magnetron with two RF outputs; 2—a tunable short-circuit waveguide; 3—a pulsed power supply (modulator); 4—ferrite isolator; 5—a generator of controlling pulses; 6—a microwave cavity; 7—a matched load (antenna).

Figure 15 shows a block diagram of the microwave module for temporal compression of the microwave pulses and generates the high power microwave radio pulses [43]. The magnetron that is used in this experiment has an active and a passive RF output ports. To tune the frequency of the magnetron, we used the tunable short-circuit waveguide as the reactive load of the passive RF output. The result of the frequency tuning under changes of a position L of the short-circuiting piston at the reactive load of the magnetron was shown in Figure 12.

The analysis shows that application of the magnetron with two RF outputs in the microwave plant for forming the high power ultrashort microwave pulses allows increasing the efficiency of compression of the microwave pulses necessary to reduce a loss of power Pr, connected with possible reflection from microwave cavity 6 for reasons of availability of existing discrepancy between the resonant frequency of a microwave cavity f <sup>0</sup> and a frequency of the magnetron. Assuming that f min , f , with the help of a short-circuiting piston, we adjust an oscillation <sup>0</sup> , f max frequency of the magnetron to a resonant frequency of the microwave cavity, and as a result, the power Pr reflected from microwave cavity is decreased.

In Figure 16, the general view of universal block diagram of the plant for generating and forming a high power microwave radiation is shown. As we notice that the radiation can be presented either as sequence of short or super-short video

#### Figure 16.

A block diagram of the high-power plant on basis of magnetron generator. 1—a source; 2—a microwave cavity; 3—a power supply; 4—antenna.

Vacuum Microwave Sources of Electromagnetic Radiation DOI: http://dx.doi.org/10.5772/intechopen.83734

pulses (case of a), or it is considered as periodical sequence of the radio-frequency pulses (case of b).

Thus, the above-mentioned examples of applying the high power generators indicate that, to date, a great demand of high power sources in many areas does not raise doubts. Also, there is a great variety of problems; the solution of which opens some new trends in the application of the high power microwave generators and the given results allow considering the employment of new designs of the mm range magnetrons and expand areas of their application in a new way.
