Multiple-Beam Klystrons and Their Use in

Complex Microwave Devices

E. A. Gelvich and A. S. Kotov

FSUE SRPC “Istok”, 141190, Fryazino, Russia

Abstract. The outstanding performance features of multi-beam klystrons enabled the application

of concepts of low power integrated circuits to high power complex microwave devices (CMD). Essential features of CMDs are individual, selective, mutual matching of all sub-components

that constitute the CMD, and operational interchangeability of the CMD as a complete system. The CMD concept has enabled a significant decrease in the mass and dimensions of radio-

electronic systems and has substantially improved their operational parameters, especially for use in mobile systems. Examples of CMDs are presented.

Keywords: Multi-beam klystrons, complex microwave devices, main features, and applications.

INTRODUCTION

The continually increasing number of functions which radio-electronic systems

(RES) must provide to meet the current needs for simultaneous radio-location, control,

and navigation of multiple objects is leading to an enormous increase of radio-

electronic equipment (REE) on board air-, sea- and land-based vehicles. Thus, the

mass and volume of a given radio-electronic system – in particular, the transmitter – is

a key decisive parameter that determines the acceptability of that system for a given

platform. Excessive size and weight are often the principal reasons that render a

particular system unacceptable for mobile, on-board applications.

The creation of an effective Multi-Beam Klystron (MBK) technology, with devices

that have demonstrated high performance while achieving a substantial reduction in

operating voltage, mass, and overall dimensions, seemed to be a solution to the

problem of system compactness. However, it was found that traditional methods of

radio-electronic equipment design did not fully exploit the performance advantages of

the MBK. To take full advantage of MBK technology and to resolve the competing

desires for increased functionality and reduced system size and weight, Complex

Microwave Devices (CMD) were developed. These devices are multifunctional

microwave units that operate at high and medium power, are designed on the

principles of integrated low power circuits, and provide the potential to create (or

receive) complex signals and amplify them to their required levels [1].

To implement these ideas, the microwave elements – including the tubes which

constitute the CMD – must have quite specific parameters in order to achieve designs

that are compact, highly efficient, and capable of fulfilling a number of different

functions in a single unit. One of the most important requirements is the ability to

65

operate at sufficiently low voltages to enable the creation of compact CMDs with

minimum mass and volume. In addition to low voltage operation, it will be further

shown that the design of CMDs itself has some inherent peculiarities, which make

them distinct from other microwave devices. The analysis of these topics is the goal

of this paper.

CMD – DEFINITION AND MAIN FEATURES

WHY USE A CMD?

First of all, a CMD is a self-contained, complete unit. It integrates all of the

necessary microwave devices (waveguide, attenuators, phase shifters, ferrite isolators,

couplers, etc.) which are mounted in (or on) a single, transportable chassis. Secondly,

a CMD is a functionally integrated device. In other words, the microwave elements

that comprise the CMD, upon being provided with the appropriate prime power and

control signals, are capable of fulfilling all of the necessary functions and can create

microwave signals with the prescribed complex parameters. In addition, a CMD is

intended to be interchangeable under operational field conditions.

Before we describe the important peculiarities of other significant features of CMD

operation, we must first consider some general common principles of RES

development.

State-of-the-art and prospective radio-electronic systems, including those intended

for mobile platforms, are intended to determine or control the location, velocity, and

acceleration of many objects simultaneously. To fulfill these functions, the system

must process large amounts of information that are contained in the amplitude, length,

and repetition rate of the pulses, and in their frequency and phase characteristics. To

generate sequences of such complicated signals with great stability and, at the same

time, provide the ability to change their parameters at any prescribed moment, chains

of more or less sequentially-connected microwave tubes are used. These tubes can

include stable oscillators (generators) with the ability to rapidly change their

frequency, frequency and phase modulators, frequency mixers, and amplifiers of

different power levels. To meet the requirements of most applications, all of these

devices must operate with a low noise level in the range of −90 to −140 dBc/Hz at 50

to 5000 Hz off the carrier frequency; a frequency instability, ∆f ⁄ f0 , in the range of

10-4

to 10-6

and lower, and have spurious oscillations of less than or equal to −60 dBc

in the output signal.

To elucidate the additional difficulties that must be surmounted to achieve the

successful design of an REE that satisfies all of the above requirements, it is useful to

explain and analyze the typical design process in further detail. One of the most

common design requirements is the demand for operational interchangeability

between a given element of the REE with any other element of the same type. The

typical parameters for a given device are spread over some predetermined interval of

values, usually according to a Gaussian distribution (see Fig. 1). Thus, the requirement

for interchangeability prescribes a particular relation between the typical parameters of

any two elements that are mutually connected in operation.

66

Such a relation is illustrated in Fig. 1, where we have an example of two

sequentially-connected tubes in an amplification chain with an adjustable device

between them. Two inferences can be made from this figure. First, the output

characteristics of Device 1 – in particular, its power – are excessive relative to the

input power required for the normal operation of Device 2. In other words, the

parameters of Device 1 are over-specified for the required application and there may

be a penalty paid in the excessive mass and volume of the device itself as well as in its

power supply. Second – and this conclusion is valid for any parameter of the devices

– the probability of an optimal coincidence of the parameter of Device 1 with the

inter-connected parameter of Device 2 is very small, especially when interchanging

devices under field operational conditions using standard procedures. This lack

coincidence of optimal parameters may lead to an erosion of the output signal quality

and, very often, to a decrease in the operational reliability of the whole complicated

microwave chain. As a result of excessive requirements, very often the mass and

overall dimensions of the sophisticated REE designed with typical matching are not

acceptable for the mobile applications (air-, sea-, or land-based).

FIGURE 1. Distribution of typically matched interconnected devices over the output (Device 1) and

optimal input (Device 2) power. PL denotes power losses in the part that interconnects Devices 1 and 2, and n is the number of devices.

However, the situation is changed drastically if the matching of the mutual

parameters of the devices in the microwave chain can be implemented during the

manufacturing process of the CMD and its constitutive devices. As opposed to field

conditions where there may be limited availability of parts, the manufacturing floor typically has access to a large number of devices with a distribution of parameters. In

this case, a skilled worker can select a set of parts that optimally match the inter-

related parameters of each sequentially-connected element of the CMD [2].

Thus, we can formulate the CMD definition in full: the CMD is a multi-functional,

constructively- and functionally-integrated device in which all elements comprising

the CMD have been carefully matched to ensure that each constituent device of the

CMD operates in its optimal regime. This functional and constructive integration,

supported by the selective matching of the elements comprising the CMD, leads to a

67

substantial decrease in the mass and volume of the microwave portion of the REE and,

in many cases, of the power supplies as well.

ANALYSIS OF MICROWAVE DEVICES SUITED

FOR OPERATION IN CMDS

The most effective CMDs are those which include all elements necessary to form a

complex microwave signal. These devices typically begin with a master oscillator or

an RF drive stage and include all elements up to the high power output amplifier.

The low-power active elements of state-of-the-art CMDs are typically integral and

monolithic semiconductor devices, including oscillators, intermediate transistor

amplifiers, mixers, phase shifters, p-i-n attenuators and switching devices,

microprocessors, etc. These elements do not have any specific requirements that are

unique to CMD applications except the demand for the mutual matching of their inter-

connected parameters.

On the other hand, the requirements for the active high-power elements of the CMD

place some important restrictions on the performance parameters of the vacuum tubes.

First of all, the goal of achieving a compact, constructively integrated device demands

that the operating voltages of the power tubes be kept as low as possible. Secondly, the

power tube must not be bulky. Thirdly, the power tubes should have sufficiently linear

characteristics so they can amplify complicated signals with sophisticated amplitude,

phase, and frequency modulations (or manipulations) over a frequency band pertinent

to the tactical needs of the RES, without distortion. And finally, the noise

characteristics of the power amplifiers must be sufficiently low to avoid the

introduction of additional noise in the Doppler frequency band used by the specific

RES.

Low operating voltages at specific power levels can be achieved with high

perveance tubes such as magnetrons, M-type amplifiers, and multiple-beam O-type

amplifiers: multi-beam klystrons (MBK) and multiple-beam traveling-wave tubes

(MB TWT). Magnetrons are typically not used in complex radio-electronic systems, as

they are oscillators and cannot therefore meet the requirement of transmitting signals

with a complicated phase-frequency structure. M-type amplifiers are nonlinear

amplifiers and their intrinsic noise levels are relatively high. Though in some cases

[3], M-type amplifiers can be used very effectively, the most typical and acceptable

class of microwave power tubes to be used in a CMD are the MBK and the MB TWT

[4].

Strictly speaking, the concept and principles of the CMD were developed and

implemented only after powerful MBKs operating in the fundamental mode of the

resonator system were developed by S.A. Zusmanovsky and S.V. Korolyov [5]. The

so-called “transparent” MB TWT was developed significantly later. As the MB TWT

amplification coefficient is much lower, and the induced noise is greater than that of

the MBK, the main power tube for CMD has been and still remains the Multi-Beam

Klystron operating in the fundamental mode.

High-power CMDs and the microwave-band MBKs capable operating in these

devices are the principal subject of our analysis in the next sections.

68

MAIN FEATURES AND PERFORMANCE PARAMETERS

OF MBKS FOR POWERFUL CMD APPLICATIONS

As maintenance and interchangeability in the field are key requirements for a

CMD, the tubes which comprise the heart of the CMD must not be too heavy and

bulky. Also, because CMDs are typically deployed on mobile platforms, they must be

volumetrically compact. These requirements place restrictions on the maximum

operating voltage of the output tube.

Compared to other classes of high power microwave amplifiers, the MBK has the

advantage of having relatively low mass and compact overall dimensions. These

features are inherent to the MBK, where the low perveance of the individual beamlets

leads to lower magnetic fields required for non-intercepting transport and thus to a

lower mass of the magnet system, and, conversely, the high total perveance of the

aggregate beams leads to a low cathode voltage and thus to reduced inter-magnet

dimensions and an additional decrease in system mass [5].

TABLE 1. Parameters of Selected MBKs Used for Operation in CMDs.

No.

Freq

uen

cy

ban

d

Pu

lsed

ou

tpu

t

pow

er (

kW

)

Du

ty c

ycle

Cath

od

e

volt

age (

kV

)

Con

trol

volt

age (

kV

)

Ban

dw

idth

(%)

Gain

(d

B)

No. of

beam

s

Pervean

ce

A/V

3/2·1

0-6

Eff

icie

ncy

(%)

Mass

wit

h

magn

et

(kg)

1 KU 25 0.09 14 3.8 2 43 15 3.8 35 8

2 X 70 0.05 13 3.5 6 43 24 8.3 39 16

3 K 0.4 0.33 2.5 0.5 0.25

1.25

50

36

18 8.0 30 0.4

4 KU 1.0 0.04 3.5 1.0 1.25 40 19 6.5 25 1.2

Table 1 [6] summarizes the parameters of a number of MBKs used in CMDs in air-,

sea-, and land-based mobile RES (in all applications, the MBK has the role of the final

output power amplifier in the CMD). Note that, in the table, the upper limit on the

mass of the MBKs (including the magnet) is ≤ 16 kg. The largest dimension of these

MBKs is ≤ 25 cm, and the cathode voltage limit is ≤ 14 kV. Yet, in spite the compact size and weight and low operating voltage, MBKs have been shown to achieve a peak

pulsed output power of 100 kW in Ku-band with 300 W of average power and up to 70

kW of pulsed output power with 3.5 kW of average power in X-band. Figures 2, 3,

and 4 are photographs of typical fundamental-mode MBKs that are used in CMDs.

69

FIGURE 2. External view of a high power, broadband MBK. The peak output power (pulsed)

is 45 kW with an average power of 1.5 kW in an amplification band of 6%.

FIGURE 3. External view of a Ku-band MBK. The peak output pulse power is 25 kW with an

average power of 1 kW. This device has a low-voltage control electrode that draws zero current.

FIGURE 4. External view of a conduction-cooled, miniature K-band MBK. The peak pulsed output power is 400 W with an average power about 150 W. Similar to the device in Fig. 3, this miniature

MBK uses a low-voltage control electrode that draws zero current.

While there are many types of high power MBKs (Ppk > 100 kW, Pav > 6 kW) in

the C- and S-bands that also operate at cathode voltages near 20 kV, their masses and

dimensions [7] are too large to be used in CMDs. In general, we can state that MBKs

of low-to-moderate power (≤ 100 kW pulse and ≤ 5 kW average) are the devices that are best suited for application in CMDs. In these power ranges, MBKs are uniquely

suited as power output devices for use in CMDs for mobile RES on all types of

platforms – air-, sea- and land-based. The low-to-moderate power CMDs can also

serve as very effective RF/microwave drivers, generating complex signals that can be

further amplified to very high power levels by high and super-high power tubes.

We now turn our attention to the generation of complex, sophisticated signals in the

CMD. As it was stated previously, these signals can be complicated pulse sequences

with amplitude, phase, and frequency modulation (or manipulation). The modulation

may be linear or nonlinear, and the corresponding pulse lengths can range from

nanoseconds up to milliseconds with repetition rates from 100 Hz to several hundred

kilohertz. The pulse carrier frequencies must be very stable ( ∆f /f ≤ 10-4

– 10-7

) and

should have the ability to be varied rapidly over a wide frequency band with response

70

times of 1–10 µs and with a low noise factor. All of these operations, including

frequency multiplication and shifting, are produced in the driving part of the CMD

using integral or monolithic semiconductor schemes. A critical issue is whether MBK

amplifiers have sufficiently linear characteristics to amplify these complicated signals

without noticeable distortions.

TABLE 2. MBK Parameters Determining the Radiated Signal Quality and Radar Capability.

[6] (©IEEE 2004)

Parameter Value Effect

Currentless pulse control voltage required to switch on

the electron beams High power MBK

Medium power MBK MMBK*)

5 to 7 kV

1.5 to 3.5 kV 0.5 to 1 kV

Flexible control of pulse duration µs to 1 ms)

and repetition rate (50 Hz to 100s of kHz)

Phase shift due to variations in

cathode voltage, Vc 7° to 12° per 1% of Vc Low modulation noise;

reasonable requirements for cathode voltage stability

Low noise close to the carrier

frequency 50 Hz off carrier

≥4 kHz off carrier

-90 dB/Hz

-110 to –140 dB/Hz

Suppression of false reflected

signals: potential enhancement of the radar;

Electromagnetic compatibility

Broad instantaneous flat bandwidth in the small-signal

regime

∆ω/ω up to 10%, depending on the

operating frequency and the signal parameters

Unperturbed amplification of short (≥0.01 µs) microwave

pulses; instantaneous operating frequency

hopping; linear frequency modulation;

electromagnetic compatibility with a number of operating

systems

Flat amplitude-frequency, highly linear phase-frequency

responses

≤5% and ±5° in a ±10 MHz interval

Unperturbed amplification of linear frequency – and phase –

modulated signals

*) Miniature MBK (MMBK)

This problem was discussed recently in [6]. In the following paragraphs, we present

a brief summary of this discussion. Table 2 [6] lists some key parameters of the

complex signals typically used in radio-electronic systems and the features of MBKs

that affect the possibility of their undistorted amplification. As it follows from the

table, we see that the most significant parameters of the microwave signal carrying the

information being transmitted to (or from) the object, can be amplified by the MBK

with minor distortion. Even more linear operation can be achieved if the MBK is

integrated into the CMD. The reason for this improvement is due to two factors. First,

by design, the MBK and the other elements in the CMD have been optimized to

operate in the optimal regime, minimizing possible distortions. Second, in the CMD,

one can add optimized feedback circuits that can compensate the MBK for nonlinear

destabilizing influences (such as environmental factors) and ensure that the MBK

remains in its optimal operational regime.

For example, there is a relationship between the value of the input power –

corresponding to the saturation regime of the klystron whereby the noise introduced

71

by the klystron is minimal – and the cathode voltage. The specific relation is different

for different models of klystrons. An advantage of the CMD is that it allows one to

choose the initial optimal relation between these parameters. Using a simple feedback

circuit that can be built into the CMD and adjusted at the factory to optimize the

performance of a specific klystron, this optimal relation can be readily maintained

under field operational conditions.

A similar situation arises with the amplification frequency bandwidth. For example,

the MBK shown in Fig. 2 has an amplification frequency bandwidth, ∆f / f, of 6%

when the operating parameters are set in the nominal regime [8]. However, changing

the cathode voltage by ± 5% decreases the ∆f / f value down to 2%. To restore the 6%

value, the input power must be changed and the magnitude of this change, ∆Pinput , is

different for each individual MBK. A simple solution is to add a voltage feedback

circuit mounted in the CMD. The feedback circuit, which is adjusted at the factory,

allows the MBK to retain its bandpass performance of 6% in the presence a cathode

voltage instability of ± 5%. This simple addition eliminates the need for a high voltage stabilizer to reduce the voltage ripple and results in substantial savings in the

mass and volume of the transmitter.

Summarizing the factors listed above, one can say that on the one hand, MBKs

have made the design of CMD devices possible while, on the other hand, the CMD has

made it possible to improve the MBK performance characteristics. Taken together,

the combination of technologies has made it possible to meet the challenge of creating

high power, multifunctional, complex radio-electronic systems adapted for operation

on air-, sea-, and land-based platforms.

Speaking about the CMD, one must firmly keep in mind that CMDs are usually

intended to solve sophisticated and, thus, relatively unique problems. The effort to

develop and manufacture each model of CMD is justified provided that the function

that the CMD provides is of vital necessity and without which the crucial parameters

of the radio-electronic system could not be achieved.

EXAMPLES OF CMDS

In this section, we present a brief review of typical CMDs developed at SRPC

Istok. The first CMD (principal designer, S.V. Korolyov) was developed in 1972-74

and was intended to serve as a two-frequency, low-noise power amplifier in an

airborne radar system. A block diagram of this CMD (CMD-I) is shown in Fig. 5.

Figure 6 presents an accompanying photograph of CMD-I. The peak pulse output

power of CMD-I, which operates in Ku-band, is 100 kW with an average power of 300

W; the corresponding gain is ≥ 60 dB. A more detailed set of parameters is given in

Table 3 [8]. A distinctive feature of CMD-I is its small mass (8 kg) and its especially

compact design. The former microwave system that CMD-I replaced was based on a

single-beam klystron and was designed using conventional design techniques; this old

design weighed 40 kg and provided operation at only one carrier frequency.

72

FIGURE 5. Block diagram of a two frequency CMD amplifier (CMD-I).

1,4 – Power splitter/combiner; 2,3 – narrowband klystron amplifiers;

5,7 – ferrite isolators; 6 – powerful MBK amplifier.

FIGURE 6. External view of a two-frequency CMD amplifier. (CMD-I)

An impressive example of the high-level parameters that can be achieved with a

CMD is the CMD amplifier CMD-II. A block diagram and accompanying photograph

are shown in Figs. 7 [8] and 8, respectively, and its parameters are listed in Table 3.

FIGURE 7. Block diagram of a high power broadband CMD amplifier (CMD-II).

73

TABLE 3. CMDs Intended for Application in Transmitters for Coherent Radars [8].

CMD type I II III IV V

Frequency band, GHz 14 7 8 9 13 …18

Amplification band, % 1,0 6 1,25 3 1,5

Pulse output power, kW 60…100 45…75 0,2 20…35 0,3…0,5

Number of operating functions 1 2 5 5 5

Pulse ratio 300 ≥20 ≥10 9…40 3

Gain, dB >60 70 - - -

Frequency multiplication by - - - 4 -

Carrier frequency switch time, µs 10 10 100

Long-term carrier frequency instability, ∆f /f

≤10-5 ≤10-4

Phase noise of the heterodyne

channel, dBc/Hz Off the carrier, kHz

Is determined by the external master

oscillator

-60 0,2

Is determined by the ex-

ternal master oscillator

-

Phase noise of the transmitter

channel, dBc/Hz Off the carrier, kHz

-130 4

-105 1

-100 0,2

-60 0,05

-130 5

Pulse length, µs 0,5…5 0,5…20 ≤60 0,1…100 0,3…7,5

Intermediate frequency, MHz - - <600 <1000 <100

MBK cathode operating voltage,

kV 21 15 2,0 11 2,5

Required voltage stability of power supply source, %

±2 ±5 ±5 ±5 ±5

Mass, kg 8 20 8 19 1,7

FIGURE 8. External view of a high power broadband CMD amplifier. (CMD-II)

FIGURE 9. Power-frequency dependence of CMD-II and of the MBK itself.

The principal elements of CMD-II are a TWT pre-amplifier, a feedback circuit

optimizing the MBK input power as a function of ±5% MBK cathode voltage

variations, and the powerful MBK amplifier.

The main characteristics of the CMD-II broadband amplifier are:

• an instantaneous amplification frequency band of 6%, allowing for wide electronic scanning of the radar beam during a single pulse;

74

• a high peak pulse power level up to 75 kW with an average power of up to 3.5

kW, enabling the detection and surveillance of small cross-section objects;

• a low noise level enabling the detection of objects close to the ground;

• a low cathode voltage level for the output amplifier and a wide range of acceptable voltage instability (±5%) resulting in a substantial decrease in the

mass and volume of the radar power supply.

In addition, the efficiency of the MBK used in this CMD is significantly higher

than that of commonly used TWTs with similar power levels and frequency

bandwidths.

The reliable operation of the MBK over the entire fractional frequency band under

the conditions of large voltage fluctuations is ensured by means of the optimizing

circuit in the CMD. Its influence on the performance of the MBK is highlighted in

Fig. 9 [8]. The ability of CMD-II operate with a non-stabilized power supply

combined with its unique performance parameters enabled the development of

multifunctional, highly-mobile radar systems with a high detection and identification

potential.

CMD-III, as presented in Fig. 10 (block diagram) and Fig. 11 (photograph) [8], is

an example of a multifunctional CMD with a lower power solid-state sub-system.

The performance parameters of CMD-III are summarized in Table 3. CMD-III

provides a power output signal, the creation of a heterodyne signal, its frequency

conversion with an up-shift of the carrier frequency, and a simultaneous instantaneous

switch of the heterodyne and output (radiated) signal to a different frequency.

FIGURE 10. Block diagram of a multifunctional multi-frequency CMD of moderate output power (CMD-III).

75

FIGURE 11. External view of a multifunctional multi-frequency CMD-III.

The main advantages of this device are the high level of frequency stability of the

output signal, fast (10 µs) and synchronous switching of the heterodyne and output

frequencies and their coherence, a low noise level in the Doppler frequency range

(starting from 50 Hz off the carrier), and the possibility of frequency and phase

modulation and low voltage amplitude modulation of the output signal. The high level

of CMD-III parameters is due to the fact that each element of the CMD has been

designed to operate in its optimum regime which is maintained during operational

conditions.

CMD-IV is representative of a class of CMDs which perform functions of

frequency multiplication and conversion, and power amplification. Figures 12 and 13

show its block diagram and external photograph, respectively. The function of this

CMD can be clearly understood from the block diagram: a stable continuous signal at

a frequency f0 , after being multiplied by a factor of four makes up the frequency, fh ,

of the heterodyne. This signal, in turn, is converted with the intermediate frequency,

Fin , and forms the radiated (output) frequency, f. Multiplication of the input signal,

f0, conversion of the signal to 4f0, and the preliminary amplification of the signal at the

output frequency f are performed by a solid-state transistor multiplier, converter and

amplifier, shown in Fig. 12. A p-i-n attenuator, controlled by an optimization feed-

back circuit (see Fig. 7), generates the optimal input value (amplitude) of the input

power, launching the high-power MBK. The amplitude modulation of the output

signal is accomplished in the MBK itself by means of its low-voltage electrode (which

draws zero current).

76

FIGURE 12. Block diagram of a multi-functional CMD (CMD-IV).

FIGURE 13. External view of a multifunctional CMD (CMD-IV).

Due to the aforementioned feedback circuit, CMD-IV is able to recover its nominal

performance parameters even when the supply voltages have fluctuations in the range

of ± 5%. The key parameters of CMD-IV are listed in Table 3.

One of the new directions of CMD development is in compact, hybrid solid-

state/vacuum CMDs for airborne applications. These devices are based on highly

efficient , compact, miniaturized MBKs (MMBK). One such example is CMD-V [9],

shown in Fig. 15. Its block diagram is depicted in Fig. 14 and its main parameters are

listed in Table 3.

FIGURE 14. Block diagram of a miniature CMD of moderate power (CMD-V).

77

FIGURE 15. External view of a miniature CMD of moderate power (CMD-V).

As was the case for all previous CMDs described in this section, CMD-V is able to

generate high quality signals even in the presence of severe operational conditions: a

frequency noise level less than −90 dBc/Hz at 5 kHz off the carrier frequency, and a carrier instability of ±10

-4. The most outstanding features are its mass (< 2 kg) and

fast turn-on time (< 10 s), producing 300 W of output power. The mechanical design

is very robust so as to allow the unit to function in severe mechanical environments.

As opposed to other CMDs described in this section, for CMD-V, the frequency shift

of the output carrier at the intermediate frequency is produced by a phase-locked loop

(PLL). This feature enables the design to achieve a low level of parasitic components

in the output signal (< −60 dBc). Amplitude modulation of the output signal is

implemented by a low voltage current-less electrode.

Finally, we emphasize again that all of the CMDs discussed in this section used an

MBK as the output amplifier.

CONCLUSION

In summary, it can be stated that the unique parameters of multiple-beam klystrons

have made it possible to create a new type of electronic instrument – the high power

Complex Microwave Device (CMD). The features which classify the CMD as an

original device type include its constructive and functional integrity and the mode of

manufacturing the device as a complete, integrated unit with its own unique rules of

design [8]. As a class of device, the CMD provides new capabilities of applications.

One of the most important and distinct features of the CMD is its ability to take

advantage of the highest levels of performance parameters from the vacuum electronic

devices that constitute the CMD. Moreover, in some cases, the device can display

qualitatively new performance characteristics that arise as a consequence of the CMD

design. This phenomenon arises from one of the main principles of CMD design –

selective matching of the individual CMD elements to ensure that each element

operates in its optimum performance regime. It must be also emphasized that the

compactness and multifunctional abilities of high power CMD has an additional

important benefit in that it enables a significant decrease in the mass and overall

dimensions of microwave signal transmitters.

78

And finally, we point out that the creation of high power CMDs is made possible in

large part to the outstanding parameters and abilities of the MBK.

REFERENCES

1. S. I. Rebrov and E. A. Gelvich, report at a Conference of Main Designers of Electronic and Radiotechnology Ministries of USSR, Zelenograd, 1975 (in Russian).

2. E. A. Gelvich, “Relation between parameters of functionally interconnected devices butted end-to-end selectively,” Electronnaya Tekhnika, Ser. 1, Electronika SVCh, no. 12, 1982 (in Russian).

3. A. N. Kargin, “Miniature frequency-locked magnetrons,” Radiotekhnika, no. 2, 2000 (in Russian). 4. A. N. Korolyov, S. A. Zeitsev, A. S. Pobedonostsev, et al., “Results of a complex theoretical investigation and

optimization of transmitting devices on the base of miniature multibeam tubes,” Elektronnaya Tekhnika, Ser.1, SVCh-tekhnika, no. 1 (483), 2004 (in Russian).

5. S. V. Korolyov, “About a possibility to decrease the mass and over-all dimensions of transient klystrons,” Elektronnaya Tekhnika, Ser.1, Electronika SVCh no. 9, 1968 (in Russian).

6. A. N. Korolyov, E. A. Gelvich, A. D. Zakurdayev, et al., “Multiple-Beam Klystron Amplifiers: Performance Parameters and Development Trends,” IEEE Trans. Plasma Science 32(3), 2004.

7. V. J. Poognin, “Power limits for high power broadband multiple-beam klystrons intended for Radar applications,” Radiotekhnika no. 2, 2000 (in Russian).

8. E. A. Gelvich and A. S. Kotov, “Complex Microwave Devices: main peculiarities and development trends,” Radiotekhnika no. 2, 2004 (in Russian).

9. A. D. Zakurdayev and A. S. Kotov, “Combined radio-transmitting Ku-band device,” Radiotekhnika no. 2, 2000 (in Russian).

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