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Item type:Publication, Access status: without files , A new class of spatial harmonic magnetrons with potentials for CW and sub-THz operation(Cambridge University Press (CUP), 2023-02-22); ; A strictly physically based design theory of a new class of Spatial Harmonic Magnetrons (SHM) is thoroughly derived which leads to analytically evaluable expressions. Thus two advantages are obtained: (1) The design parameters appear grouped into two separate categories - one just containing geometrical and material parameters, the other one exclusively containing beam current-related ones, which are in product-form determining performance. The influence of each parameter can thus easily be discovered and investigated. (2) Numerical efforts for any new design will be reduced by at least one order of magnitude. Subsequently and based on feature (1) it is derived that loading the anode structure by a suitably selected meta-material will increase output power and efficiency, will pave the way to CW operation, and can extend oscillation frequency well into the sub-THz range. Finally, it is shown that the Rising Sun Magnetron is a first step toward a meta-material loaded SHM offering the same but quantitatively reduced features and less stringent requirements to fabrication technology.Publicationtype: Journal Article40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Double Frequency Retrieval of Rain Intensity Using Solution of the Integral Equation of Scattering(2020-09-21); ; A solution for the inverse problem of rain remote sensing presented by Fredholm integral equation of the first kind is proposed in the case of microwave double frequency sensing and Tikhonov regularization. Performed numerical simulation showed that proposed approach permits to retrieve the rain intensity with error less than 20 % for rain intensities more than 5 mm/h and with an error of 60 % for intensities less than 5 mm/h (modeling was performed for radar operating wavelengths 0.82 and 3.2 cm and for a range of rain intensity 1 ÷ 30 mm/h).Publicationtype: Conference Paper113 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Prediction algorithm of the receiving antenna location for quasi-optical circuit componentsQuasi-optical beam forming structures are very interesting and involve different kinds of methods for their analysis. In order to optimize the cost function of our target solution, it is important to develop a predictive system to determine where the receiving antenna should be located for more efficient propagation of electromagnetic waves. Solving this antenna problem with the mathematical theory of diffraction is a complicated task due to the involved integrals with hyper-singular singularities in their kernels. This has raised the objective to develop a discrete mathematical model which could solve those difficulties.Publicationtype: Journal Article246 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Controlling the oscillator frequency synchronization by a low-frequency drive(2017-12-19); ; The dynamics of an oscillator driven by both low- and high-frequency external signals are studied. It is shown that both two- and three-frequency resonances arise due to a nonlinear interaction of these harmonic forces. Conditions which must be met for oscillator synchronization under these resonances are estimated analytically by considering the Van der Pol oscillator with modulated natural frequency as mathematical model. It is demonstrated that due to the low-frequency modulation, additional synchronization regions arise in the control parameter space. Feasibility of the theoretical findings is confirmed in experiments with a Hartley-type oscillator.Publicationtype: Conference Paper94 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Advances in spatial-harmonic magnetrons with cold secondary-emission cathode(IEEE, 2017-12-19); ; ; ; The spatial-harmonic magnetron with cold secondary-emission cathode is an effective source of radiation up to 210 GHz frequency range. State of the art in the design, realization, and investigation of such magnetrons is described. Examples of the successful developments of low-voltage tubes, tubes with a long output pulse duration, and Sub-THz magnetrons are presented in more detail.Publicationtype: Conference Paper85 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Ka-band geophysical model function(2017-12); ; A Ka-band geophysical model function is proposed. The model function is based on a similar previously-developed backscatter model, which showed a disadvantage at near cross-wind azimuths for incidence angles of 47° to 50°. The new Ka-band geophysical model function is valid for incidence angles of 30° to 50° at vertical transmit and receive polarization. Several particular cases of water-surface backscattering are presented by using this function.Publicationtype: Journal Article64 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Controlling the characteristics of nanomechanical resonators(2016-12-07); ; The dynamics of nanomechanical resonators driven by both low- and high-frequency signals is studied. Considering, as an example, resonators made of a doubly-clamped beam with magnetomotive driving, it is shown that three-frequency resonances arise due to the interaction of the above frequencies. Properties and characteristics of these resonances are determined analytically for linear and nonlinear modes of the resonator excitation. It is shown that in opposite to the conventional two-frequency resonance, the central frequency of these resonances, their linear dynamic range, and the critical value for the bistability onset are easily controlled by changing the frequency and the amplitude of the low-frequency driving current. The obtained results can be used when developing NMRs for sensors, filters, memory elements, and other applications.Publicationtype: Conference Paper102 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Spatial-harmonic magnetrons with cold secondary-emission cathode: advances and challenges(2016-08-11); ; Spatial-harmonic magnetrons with cold secondary-emission cathode are efficient high-power millimeter-wavelength oscillators. Recent advances in the development of such low-voltage magnetrons, 210 GHz tubes, and magnetrons with an extended lifetime are reviewed. Potentials for further improving the performance of spatial-harmonic magnetrons are considered as well.Publicationtype: Conference Paper60 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Three-frequency resonances in single-mode systems(2016-08-09); ; We review recent results on the interaction of low- and high-frequency oscillations that lead to arising of three-frequency resonances in nonlinear oscillators. The Duffing oscillator and the Van der Pol oscillator both with modulated natural frequency and a high-frequency harmonic forcing are considered as examples to illustrate and study this phenomenon. It is shown that such interaction enables an efficient control of the oscillators dynamics and their properties. The formation of bistable states and synchronous oscillations is considered in detail.Publicationtype: Conference Paper65 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Epsilon near zero loaded magnetrons, design and realizationIn this paper, it is shown that employing the unit cell of an ENZ (epsilon near zero) medium in the slow wave structure of a spatial harmonic magnetron (SHM) can moderate the conflict between the simultaneous realization of large values of the quality factor and of the characteristic admittance which is a well-known issue in classical and spatial harmonic magnetrons. As the numerical simulations of the beam-wave interaction shows, simultaneous increase of the characteristic admittance and the quality factor makes the metamaterial loaded SHM superior to its conventional counterpart. The preliminary measurement results of the fabricated metamaterial loaded SHM are also presented in this paper.Publicationtype: Conference Paper27