TWT Model on a Metamagnetic Plate
A model of the traveling-wave tube (TWT) that includes a magnetic plate with increased permeability and a metal screen parallel to the plate is considered. The dispersion equation in the presence of a homogeneous electron beam (e-beam) filling the space between the plate and the screen is derived. The method of differentiation of the dispersion equation in the presence of the e-beam is used to calculate coupling and depression coefficients, entering the TWT characteristic (determinantal) equation. The consideredmodel is comparedwith a similarmodel on a dielectric plate and “impedance” comb model. Conclusions concerning the prospects of development of such a “magnetic” TWT are drawn.
A TWT model formed by a meta-magnetic plate and a metal screen is offered and analyzed. The dispersion equation of the model in the presence of a homogeneous electron beam filling the space between the plate and the screen is derived and solved. The coupling and depression coefficients are calculated by the method of differentiation the dispersion equation. The calculated characteristics are compared with the TWT models on a dielectric plate and an “impedance” comb.
The effect of dielectric supports on the slowing factor and dispersion of the helical line in TWT is considered. A method for the calculation of the slowing down in the helical line with the complicated configuration of the dielectric supports is proposed. A procedure for the experimental study of dispersion in the helical slow_wave system is presented. The calculated results are compared with the experimental data.
Currently, frequency selective surfaces, based on metamaterials are increasingly important in microwave technique. The mushroom-type metamaterial surfaces allow solving such tasks as isolation of elements in antenna arrays, multipath mitigating in GNSS systems, reduction of the ground plane edge influence on the directivity of the antenna elements etc. The usage of these structures in the microwave devices design can significantly improve their properties and performance. Structurally mushroom-type metamaterials are periodic microstrip structures and their properties depend strongly on the parameters of the substrate and the accuracy of manufacturing of the conductive pattern. As these structures have a narrow band gap, expensive materials and high precision technologies should be used for their manufacturing. A method of the mushroom-type metamaterial band gap electronic readjustment is proposed in this paper. The idea of the method is that a variable-capacitance diode, should be placed between two coupled mushroom hats one terminal of which is grounded for direct current through a metalized via of the metamaterial element, and the other one is connected to a controlled DC voltage source. At the same time the mushroom hats are separated by at least two capacitive gaps, one of which is in parallel with a variable-capacitance diode, which equivalent capacitance is determined by the DC voltage of the controlled source. The design of a band gap metamaterial-based frequency selective surface with an electronic readjustment of the working band, and the results of its numerical modeling, which show the working band frequency movement while the changing of the lumped elements capacitance are presented. The calculation of the structure dielectric parameters, which confirms that the proposed structure is a metamaterial, is provided.
Propagation of the short vector envelope solitons in a inhomogeneous medium with linear potential in coupled third–order nonlinear Shrodinger equations frame is considered. Explicit vector soliton solution is obtained. The explicit solution for the solitons trajectories is studied. In particular cases this solitons solution can be reduced as to the short scalar soliton solution on linear inhomogeneity profile, as to well – known Chen soliton solution.
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.