Investigation of a Frequency-Selective Surface Based on a Planar Mushroom-Shaped Metamaterial with an Electronically Tunable Stopband
A design of a band-stop frequency-selective surface based on a planar mushroom-shaped metamaterial with an electronically tunable stopband has been proposed and investigated. The results of numerical simulation and experimental measurements of the parameters of a finite section of the metamaterial with mounted varicaps are presented. These results illustrate the shift of the structure stopband occurring simultaneously with a change in the capacitance of the lumped elements. Frequency dependences of the inherent dielectric parameters have been obtained. They indicate the presence of negative values of the effective permittivity and effective permeability of the proposed structure and the presence of the surface impedance that significantly exceeds the free-space characteristic impedance and is frequency-tunable.
Methods for extension of the rejection band of microwave devices on the basis of planar modified mushroom-shaped metamaterials comprising either two-layered topological structures with frequency-selective surfaces or multilayer bulk structures with intermediate layers containing split-ring resonators are proposed. Computer simulation of such devices, clearly demonstrating a twoto six-fold extension of the rejection band is performed. Experimental results confirming the results of numerical simulation are presented.
The scientific paper is dedicated to the investigation of a rectangular waveguide R32 type with magnetic wall of mushroom-shaped metamaterial supplemented by a dielectric substrate. The computer model of the waveguide filter under consideration and its quantitative characteristics of S-parameters and voltage standing wave ratio received are presented. All collected data are appropriately organized in terms of convenience to compare the figures and submitted as the frequency dependence plots which are more representative and straightforward for analysis. Based on the results obtained it is possible to make assumptions about the qualitative transformation of waveguide properties under the influence of a mushroom-shaped metamaterial and prospects for a future integration this construction in the microwave devices. This groundbreaking treatment could be an underlying solution to the problem of miniaturization and performance in the modern technology development.The scientific paper is dedicated to the investigation of a rectangular waveguide R32 type with magnetic wall of mushroom-shaped metamaterial supplemented by a dielectric substrate. The computer model of the waveguide filter under consideration and its quantitative characteristics of S-parameters and voltage standing wave ratio received are presented. All collected data are appropriately organized in terms of convenience to compare the figures and submitted as the frequency dependence plots which are more representative and straightforward for analysis. Based on the results obtained it is possible to make assumptions about the qualitative transformation of waveguide properties under the influence of a mushroom-shaped metamaterial and prospects for a future integration this construction in the microwave devices. This groundbreaking treatment could be an underlying solution to the problem of miniaturization and performance in the modern technology development.
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.
Waveguide termination modeling with a mushroom-shaped wall were carried out. Voltage standingwave ratio (VSWR) and reflection coefficient (S11) frequency dependencies were obtained. High values of the mushroomshaped structure unloaded quality factor are the main advantage of explored design. The using of distributed LC resonant circuit with dimensions which significantly smaller than wavelength allows creating a compact termination working in microwave range.
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.