Klausst 72fvm 36betwixt 22 reflex klystron, volker muehlhaus 21asdf44 the process is referred to as modulation. The amount the frequency can be varied above or below the center frequency is limited by the halfpower points of the mode, as shown in figure 212. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. The development of reflex klystron as local oscillator. This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam.
May 02, 2020 microwave engineering lab viva question bank, engineering edurev notes is made by best teachers of. In order to generate microwave frequencies we need amplifiers or oscillators,in this video we will learn how a reflex klystron oscillator works in generation of microwave frequencies. Early in 1940 british had taken the decision to build radiolocalization sets operating around 10 cm. What is the operating frequency and power output of a reflex klystron. In the case of electronic tuning circuit, the control can be brought about by using a waveguide or microwave cavity or varactor diode or yig sphere. It is a lowpower device used primarily for two purposes. Dhanalakshmi college of engineering department of ece. The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity but here the similarity ends. This is most widely used in applications where variable frequency is desired as. Klystron multi cavity klystron, reflex klystron, working. All these components are enclosed in a glass envelope. The present description refers to xbnd 2k25 reflex klystron oscillators, but most of the components can be used with other tubes employing the same operating voltages. The analysis is similar to earlier explanations of electron bunching in a fieldfree drift space and predicts a similar current distribution when bunching takes place in a reflecting field. A comprehensive analysis of reflex klystrons is developed by considering the electrons as particles acted upon by forces which modify their motion.
The reflex klystron is a single cavity variable frequency microwave generator of low power and low efficiency. The paper describes a reflex klystron oscillator, tunable over the wavelength range of 89 mm, which is suitable both for use in a superheterodyne receiver and as a source for laboratory measurements. Reflex klystron reduced power from the bunches, in reflex klystron, reduces the reflex klystron of the cavity oscillations and causes a decrease in output power. The cavity operates in its fundamental mode and tunes smoothly over the wavelength band. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. Electronic tuning is also possible, by adjustment of the repeller voltage. Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable. As shown in the given diagram it is composed of heater, cathode, focusing electrodes and repeller anode. A klystron is a vacuum tube that can be used either as a generator or as an amplifier of power, at microwave frequencies klystron types there are two basic configurations of klystron tubes 1.
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. It had its beginnings in europe and russia in the early 1930s. The work was advanced by the spacechargewave propagation theory of hahn and ramo l in 1939 and con. This tube is called a reflex klystron because it repels the input supply or performs the opposite function of a klystron. At birmingham a group of scientist leaded by professor mark oliphant was working since 1939 on power transmitting klystrons, based upon information and prototypes of the velocity modulated.
The selfoscillation and stationary oscillation conditions are analyzed theoretically. Cavities used in a twocavity klystron have high q values with narrow bandwidths, and thus, individual tuning is awkward. What is the range of frequency variation of reflex klystron in the xband by the above two methods. 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. History the fundamental principle behind the klystron, velocity modulation, has an interesting history. Reflex klystron the analysis of a reflex klystron is similar to that. This wave shape is useful for changing sweeping the. The microwave oscillations are coupled out by means of an inductive pickup loop and fed through the short section of coaxial line shown on the lefthand side of the cavity. Microwave engineering reflex klystron tutorialspoint. The complex dynamics of a model doublecavity delayed feedback klystron oscillator is considered. Here we will discuss oscillators based on semiconductor devices. Klystrons are used as amplifiers at microwave and radio frequencies to produce both lowpower reference signals for superheterodyne radar receivers and to produce highpower carrier waves for communications and the driving force for modern particle accelerator s klystron amplifiers have the advantage over the. To study the mode characteristics of the reflex klystron tube and to determine its electronic tuning range. The reflex klystron also known as a sutton tube after one of its inventors, robert sutton was a low power klystron tube with a single cavity, which functioned as an oscillator.
The reflex klystron contains a reflector plate, referred to as the. The main difference between two cavity reflex klystron amplifier. What is mechanical tuning and electronic tuning in a reflex klystron. From each mode and the band of frequencies over which the circuit can be tuned. A sutton tube, or reflex klystron, is a type of vacuum tube used to generate microwaves. Therefore, two cavity klystrons are generally used for fixedfrequency applications. The tuning range is about 8 mhz at x band and 80 mhz for submillimeter klystrons. To study the characteristics of the reflex klystron tube and to determine the its electronic tuning range equipments klystron power supply, klystron with mount, isolator, frequency meter, variable attenuator, xband detector, bnctobnc cable and oscilloscope theory reflex klystron is one of the most commonly used microwave low power generators. Microwave frequencies are millimeter waves so we need to generate them through amplifiers or oscillators,in this video we will learn generation of microwave frequencies using reflex klystron.
From each mode and the band of frequencies over which the circuit can be. Experiment4 study of the characteristics of the klystron tube. I think u1 may have to do with getting the reflex klystron started. Reflex klystron telecommunications engineering mechanics. The theory of the twocavity klystron can be applied to the nalysis of the reflex klystron with slight modification. Reflex klystron used as a lowpower microwave oscillator 2. It is mounted in a metal envelope having a glass window through which the output power passes. Reflex klystron oscillator operation application of. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. Such mechanical tuning of reflex klystron oscillator may give a frequency variation which ranges in practice from 20 mhz at x band to 4 ghz at 200 ghz. Klystron tube article about klystron tube by the free. The reflex klystron makes use of velocity modulation to transform a continuous electron beam into.
Klystron oscillator reflex klystron traveling wave tube magnetron. After the focusing electrodes there is a cavity resonator which encircles the glass envelope. Us2944183a us636261a us63626157a us2944183a us 2944183 a us2944183 a us 2944183a us 636261 a us636261 a us 636261a us 63626157 a us63626157 a us 63626157a us 2944183 a us2944183 a us 2944183a authority us united states prior art keywords cavity coupling secondary iris resonator prior art date 19570125 legal status the legal status is an assumption and is not a legal. This problem of tuning is responsible, to a large extent, for the fact that of all forms of klystrons, by far the most common is the reflex klystron which utilizes only one resonant cavity. Coates 200720 the actual value of m depends on how effectively the two inductors are magnetically coupled, which among other factors depends on the spacing between the inductors, the number of turns on each inductor, the dimensions of each coil and the material of the common core. As reflex klystrons are oscillators thus find applications in local oscillators receivers, radar receivers, radio receivers. Coates 200720 sweep oscillators a sweep waveform is another name for a sawtooth wave. Oscillators are used to generate coherent sinusoidal waveforms which may be used to transmit information or energy. They are used as 1 signal source in microwave generators.
This is the reflex klystron oscillator, which will now be described. Timedomain particleincell modeling of delayed feedback klystron oscillators article pdf available in ieee transactions on electron devices 616. Klystron oscillators are used mainly in parametric amplifiers and in radio beacons with wavelengths in the centimeter or millimeter range. Comparing the mechanism of reflex klystron and barkhausenkurz oscillators, we found them principally to be the same. Sylvanias reflex klystron is designed to operate at wavelengths be tween 67 cm. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. By the way, the idea of factory installed and adjusted cavities was accepted also by. Normally we use separate components in devices such as radio transmitters and receivers but as frequencies increase the two components merge into one structure and become a. The sutton tube, the first reflex klystron oscillator.
It is possible to produce oscillations in a klystron device which has only one cavity, through which electrons pass twice. The reflex klystron oscillator is a lowpower, lowefficiency microwave oscillator, illustrated schematically in figure 118. The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity, but here the similarity ends. As power oscillator 5 50 ghz if used as a klystron amplifier. What is the maximum theoretical efficiency of the reflex klystron. Multi cavity klystron two cavity klystronused as lowpower. Some modifications and additions have been made in the interest of flexibility and ease of adjustment. In the case of gunn oscillators, the oscillation frequency primarily depends on the middle active layer of the gunn diode. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons.
There are often several regions of reflector voltage where the reflex klystron will oscillate. The 2k28 reflex klystron has a lead protruding through the top of the glass envelope which is used to connect the reflector voltage to the tube. Caryotakis, performance of a 150mw sband klystron, aip conf. Us2944183a internal cavity reflex klystron tuned by a. Just how this is accomplished may be seen by considering fig. The tuning range of klystron lies between 5 ghz at 2w to 30 ghz at 10 mw.
However the resonant frequency can be tuned externally either by mechanical or by electrical means. Klystron article about klystron by the free dictionary. To understand the operation of a reflex klystron i think you need to start with a basic understanding of a tuned circuit made up from a capacitor c and inductor l. Electronic tuning and output power of a reflex klystron.
A schematic diagram of the reflex klystron is shown in fig. It was used as a local oscillator in some radar receivers and a modulator in microwave transmitters the 1950s and 1960s, but is now obsolete, replaced by semiconductor microwave devices. Pdf complex dynamics of a doublecavity delayed feedback. Electronic tuning does not change the center frequency of the cavity, but does vary the frequency within the mode of operation.
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