Microwave engineering cavity klystron tutorialspoint. It focuses on the needs of students who take up the subject at undergraduate and postgraduate levels selection from microwave and radar engineering book. Reflex klystron how does this affect the efficiency of the magnetron. Reflex klystron working, oscillator and applegate diagram youtube. In this video, i have explained reflex klystron with following points 1.
Reflex klystron working free download as powerpoint presentation. Explain the working principle of reflex klystron and derive expression for power and efficiency. So, electron beam is injected from the cathode and that injected beam travel with a uniform velocity till the cavity. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. This type of a klystron is called a reflex klystron because of the reflex action of the electron. What are the various modes of operation in the reflex klystron. Yes, they had a bellows that was externally adjusted to cause the separation between grids that coupled to a resonant chamber as reflex. Reflex klystron oscillator 11 working the feedback necessary for electrical oscillations is developed by reflecting the electron beam, the velocity modulated electron beam does not actually reach the repeller plate, but is repelled back by the negative voltage. This type of a klystron is called a reflex klystron because of the reflex action of the. Explain the principle of operation of reflex klystron oscillator with a neat diagram.
Klystron amplification, power output, and efficiency can be greatly improved by the addition of intermediate cavities between the input and output cavities of the basic klystron. What is the difference between velocity modulation and current density modulation. Klystron works on the principle of velocity modulation of electrons. Reflex klystron is a microwave device that works on principle of velocity modulation in addition to current modulation.
An electronic oscillator can also be made from a klystron tube when the second cavity resonator is fed back to the first one with a coaxial cable or waveguide. In klystron strong electrostatic fields are required for its operation efficiently. A gunn diode oscillator also known as a gunn oscillators or transferred electron device oscillator are a cheap source of microwave power and comprise of gunn diode or transferred electron device ted as their major component. Need cavity oscillator basics, circuit designing and its implementation in multisim if. It was the first working klystron that physicists and engineers there had been able to observe. A singlecavity klystron in which the electron beam is reflected back through the cavity resonator by a repelling electrode having a negative voltage. The twocavity klystron is a widely used microwave amplifier operated by the principles of velocity and density modulation. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. Two cavity klystron amplifier principle velocity modulated tube high. The focusing electrodes keep the flow of electrons in the center of glass envelope. Klystron with modefrequency characteristics and also explaining two cavity klystron and two cavity klystron working.
The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. S c j x waveguide wr284 wr229 wr7 wr90 length mm 240 mm 190 mm 170 mm mm travel 75 mm 60mm. Experiment 1 measurement of frequency and wavelength. Important question and answers on reflex klystron with.
This connection must have a defined delay so that the. Reflex klystron used as a lowpower microwave oscillator 2. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. On this channel you can get education and knowledge for general issues and topics. Experiment 1 measurement of frequency and wavelength objective to determine the frequency and wavelength in a rectangular waveguide working in te 10 mode equipments klystron tube, klystron power supply, klystron mount, isolator, frequency meter, variable attenuator, slotted. Microwave engineering ece questions and answers page 6. So, working principle of reflex klystron is velocity and current modulation. Klystron article about klystron by the free dictionary. Ece questions and answers on microwave engineering with explanation for various interview, competitive examination and entrance test. When we switch on the klystron, the heater of reflex klystron is heated up.
Klystron multi cavity klystron, reflex klystron, working. The reflex klystron contains a reflector plate, referred to as the. Reflex klystrons were developed in 1940 by the soviet engineers n. When switch on the circuit, the electrons starts emitting from the cathode.
A reflex klystron is an obsolete type in which the electron beam was reflected back along its path by a. Working the first grid next to the cathode controls the number of electrons in the electron beam and focuses the beam. Explain the oscillation mechanism and the electron trajectory concept of magnetron oscillator. They propagate in free space freely means that attenuation in free space is small. The basic principle of operation of the microwave tubes involves a transfer of power from a.
Reflex klystron telecommunications engineering mechanics. Moreover it uses repeller inplace of catcher cavity. A klystron is a specialized linearbeam vacuum tube evacuated electron tube the name klystron comes from the stem form. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. So, electron beam is injected from the cathode and that injected beam travel with a. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Reflex klystron free download as powerpoint presentation.
Pdf optimization of micromachined reflex klystrons for operation. The klystron was the first embodiment of the velocity modulation principle. The first papers on the theory of the reflex klystron were published by the soviet physicists ia. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. Modern semiconductor technology has effectively replaced the reflex klystron in most applications. Reflex klystron article about reflex klystron by the. From each mode and the band of frequencies over which the circuit can be. A reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram. What happens to the power output as the repeller voltage increases. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. The main difference between two cavity reflex klystron amplifier. Twystron is a hybrid amplifier which uses a combination of klystron and slow wave structures. I was an aetm3c in the navy and also remember those local oscillators.
Their work was preceded by the description of velocity modulation by a. Recent listings manufacturer directory get instant insight into any electronic component. Microwave and radar engineering presents the essential features of microwave and radar engineering. Typical operational problems with a klystron input drive power is too low and klystron is not saturated although this is required if the tube is included in a feedback loop reduced output power, efficiency, and increased output power amplitude jitter wrong cathode filament current wrong perveance. The reflex klystron makes use of velocity modulation to transform a continuous electron beam into.
A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical engineers russell and sigurd varian, which is used as an amplifier for high radio frequencies, from uhf up into the microwave range. The power output is high in the first mode of operation of the reflex klystron. Article pdf available in ieee transactions on microwave theory and techniques. Slow wave structures are also otype but have nonresonant periodic structures for electron interactions. They perform a similiar funciton as reflex klystron oscillators. With the applegate diagram, describe the mechanism of operation of two cavity klystron amplifier. These electrons move at a uniform speed towards the anode until they are attracted by it. What is the basic principle involved in microwave tubes. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. The reflex klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29.
High velocity electron beam is generated by an electron gun and sent down along a gas tube through an input cavity buncher, drift space field free and an output cavity catcher to a collector electrode anode. Piskunov, working as a group, and, independently, by the soviet engineer v. Maximum power is obtained by proper tuning of short matching the impedance of waveguide to the klystron tube. The brothers russell and sigurd varian of stanford university are the. Reflex klystron working, oscillator and applegate diagram. Reflex klystron amplifier electronics club microwave engineering. Microwave engineering reflex klystron tutorialspoint. The application for klystron with integral cavities is usually credited in the early 1939 to hahn and metcalf and to russell and sigurd varian, two brothers that.
This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. Home lab manual lecture notes about us contact sitemap privacy. Explain the working principle of reflex klystron and derive expression of bunching parameter nd. Most applications of microwave technology make use of frequencies in the 1 to. Other articles where twocavity klystron is discussed. For free materials of different engineering subjects use my android. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids.
In wikipedia it says that, the electrons are fired into one end of the tube by an electron gun. Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable. In gunn oscillators, the gunn diode will be placed in a resonant cavity. Because of security restrictions, which had been imposed by sperry for industrial reasons and by the national defense research council, little was known about this new microwave tube. The reflex klystron oscillator is a vacuum tube microwave signal generator and its operation depends on the principle of velocity modulation and transit time. Ph0101 unit 2 lecture 6 4 working the cathode emits electrons which are accelerated forward by an accelerating grid with a positive voltage on it and focused into a narrow beam.
The principle of velocityvariation, first used in heil oscillators, was also used in other microwave amplifying and oscillating tubes. Harrison, klystron technical manual, sperry gyro scope company. Dhanalakshmi college of engineering department of ece. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. What are the assumptions for calculation of rf power in reflex klystron. Answers pls post the operation of reflex klystron and klystron tubes. Why is pulse modulation required in reflex klystron. F input signal to the buncher cavity with the help of loop coupling. Reflex klystron is a single cavity variable frequency generator of low power and low efficiency. Reflex klystron is also known as a sutton klystron. Nd 15 reflex klystron if a fraction of the output power is fed back to the input cavity and if the loop gain has a magnitude of unity with a phase shift of multiple 27t, the klystron will oscillate. I have a doubt on how exactly a reflex klystron worksas an rf source. The voltage accelerates the dc electron beam to a high. The working of reflex klystron is somewhat similar to the working of twocavity klystron.
90 384 681 1400 1036 1332 1463 370 824 810 663 1256 754 1295 1374 108 367 1446 469 1352 1039 478 202 294 1005 1432 787 55 568 1035 638 772 845 149 709 1135 1301 478 1374 41 1277 148 1389 922 1175