multiple-beam klystrons and their use in complex...
Post on 28-Feb-2020
15 Views
Preview:
TRANSCRIPT
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).
79
top related