О возможности одновременного усиления нескольких телевизионных каналов широкополосной мощной ЛБВ
The possibilities of use as the output stage television transmitter traveling wave tube to amplify simultaneously several television channels. TWT has a wide bandwidth and a high gain. The simulation of the transformation of multi-frequency signals, including a lest of the television signal. The method of analysis — a quasistationary. Lamp determined by its amplitude and fazo-amplitude external characteristics. The case of sufficiently smooth characteristics that can be approximated by a polynomial of low degree. For a given bandwidth requirements for high-frequency signal and intermodulafion interference investigated for optimal arrangement of three to six TV channels in a given band TWT. We also consider the effect of the phase of each channel at the level of the Raman background.
It is shown that the use of the phase shifter on the even (or odd) channels to reduce intermodulation background caused by combination up to 5 dB at the same total power. The calculations of the nonlinear interaction of the six channels, received frequency and levels of combinational components with different capacities and placement of frequency channels. We give conditions for selection of the total input power TWT in which intermodulation interference is less than the level specified by the standard.
This paper considers the model of amplification of electromagnetic millimeter waves by non-relativistic electron beams in one-dimensional periodic electrodynamic systems. As slow-wave structures are investigated systems such as “winding waveguide” and “counter-pins”-type suitable for use in the millimeter range. The main directions of research are: - development of a traveling-wave tube model on the basis of the differential theory of excitation of electrodynamic systems by currents; - modeling and calculation for simplified waveguide-resonator model of electrodynamic properties of slow-wave structures such as "winding waveguide" in the millimeter range; - representation of a waveguide-resonator model of "winding waveguide"-type slow-wave structure, composed of segments of rectangular and U-shaped waveguide; - obtaining by a waveguide-resonator model coefficients of the transmission matrix, which allows to analyze the dispersion and coupling impedance in the band of amplified frequencies; - investigation of “winding waveguide"-type slow-wave structure taking into account the geometric phase rotation field in neighboring gaps by linear waveguide-resonator model represented by a chain of quadripoles by means of opposite switching of the induced current in the neighboring interaction gaps and also the first spatial harmonic used in traveling-wave tubes for the calculation of the dispersion; - calculation of a number of options that characterize the basic laws of changes in the properties of “winding waveguide"-type slow-wave structure; - modeling the properties of slow-wave structures such as "winding waveguide" using 3D-codes; - application of the results obtained using the 3D-codes as the numerical experiment to adjust waveguide-resonator model; - model building pin-type slow-wave structures using waveguide-resonator model, customized by experimental reference points. The paper shows that for modeling slow-wave structures such as “winding waveguide” and “counter-pins” waveguide-resonator model customized to the experimentally obtained reference points can be used. As the reference points can also be used the values of deceleration and the coupling impedance obtained by numerical experiment using HFSS. Waveguide resonator models constructed in such way are sufficiently accurate and simple. This paper shows that these models can be successfully used for the calculation of traveling-wave tubes operating in the millimeter range.
In this paper, a model describing the discrete interaction of a traveling-wave tube (TWT) with resonator slow-wave structures (SWSs) is considered. The problems of development of TWT are analyzed, and the approaches to finding solutions for these problems are considered. When simulating a TWT section, a chain of sextapoles with combined field and current terminals is used. The developed model served as a basis for the development of the software complex VEGA which will be used later for the design of TWT in microwave and EHF bands.
Traveling wave tubes are actively used in various radio transmitting devices. However, the analysis of modern literature sources showed that there are no mathematical models that allow to take into account the influence of technical parameters of traveling wave tubes on the failure rate, and, as a consequence, on the time to failure and resource.
The suppression of the nonlinear distortions in amplifier using the effect of the envelope signal of the amplified HF oscillations on the amplifier parameters is analyzed. A slow (on the time scale of the HF oscillations) variation in the parameters gives rise to additional frequency components of oscillations that compensate for the nonlinear distortions of the original signal. Several variants to employ the compensating signal using the feedback circuits in the transistor amplifiers and variations in the electron-beam current in TWT in the absence of such circuits are considered. The suppression of the nonlinear intermodulation distortions (IMDs) of the test two_frequency signal is studied for the above variants and the suppression of the third_order IMD by 6–19 dB corresponds to the known experimental data on the microwave transistor amplifier. The generalization of the quasistationary method for the analysis of the nonlinear transformation of signals allows the analysis of the amplification and suppression of IMD for more complicated multifrequency signals that are used in radio systems.
The transmission of а complex signal through nonlinear structures (semiconductor diodes, high-power transistor amplifiers, microwave vacuum amplifiers, ets.) is investigated by means of quasi-stationary method, and functional models of devices are applied. The models use the quasi-stationary method of analysis of multifrequency signal transformation. Certain properties and peculiarities that are exhibited by nonlinear devices and that induce so-called spectrum multiplexing, i.e., formation of combination components, including those observed within the basic spectrum, are considered. The possibilities of spectrum multiplexing in nonlinear elements with a polynomial quadratic, cubic, or more complicated characteristic are discussed.
A linear theory of the discrete interaction of electron beams and electromagnetic waves in slow-wave structures (SWS) is developed. The theory is based on the finite_difference equations of SWS excitation.The local coupling impedance entering these equations characterizes the field intensity excited by the electron beam in interaction gaps and has a finite value at SWS cutoff frequencies. The theory uniformly describes the electron–wave interaction in SWS passbands and stopbands without using equivalent circuits, a circumstance that allows considering the processes in the vicinity of cutoff frequencies and switching from the Cerenkov mechanism of interaction in a traveling wave tube to the klystron mechanism when passing to SWS stopbands. The features of the equations of the discrete electron–wave interaction in pseudoperiodic SWSs are analyzed.
Generalized error-locating codes are discussed. An algorithm for calculation of the upper bound of the probability of erroneous decoding for known code parameters and the input error probability is given. Based on this algorithm, an algorithm for selection of the code parameters for a specified design and input and output error probabilities is constructed. The lower bound of the probability of erroneous decoding is given. Examples of the dependence of the probability of erroneous decoding on the input error probability are given and the behavior of the obtained curves is explained.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.