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ABSTRACT: This paper presents various applications where wide-band signals are the dominant factor. The approaches applied here are based on the present knowledge in the field of white light theory (the THz band), the particle theory of light, and the wave theory of light. White light theory is used to investigate wide-band applications of non-coherent electromagnetic waves in the GHz range represented by noise. In addition, the theoretical approaches to the field of white light are confirmed by various experiments with noise fields applied in the GHz range. These experiments show clear advantages of measurements performed by means of noise fields. The most important feature of these fields is the absence of interference effects.
Progress In Electromagnetics Research. 01/2011; 111:311-330.
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ABSTRACT: This paper studies a combination of electric and magnetic particles in order to obtain simultaneously negative electric and magnetic polarisability under irradiation by an electromagnetic wave. The magnetic particle is represented by a split ring resonator, and electric particle is represented by an electric dipole terminated by an inductor. They are combined together in a way that obtains a resonant element with inversion symmetry. The internal coupling between these resonators located in a waveguide is subjected to a special study. The response of this particle is strongly anisotropic, but an isotropic response can be achieved by a proper spatial arrangement.
Microwave Conference (EuMC), 2010 European; 10/2010
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ABSTRACT: The perfectly conducting stacked fishnet metamaterial is studied in this paper. The analysis is based on a combination of the mode matching method together with the generalized eigenvalue problem, and takes into account wave propagation along all three Cartesian axes. The analysis has been developed for a fishnet of square lateral periodicity and for two particular polarizations, namely TE and TM, corresponding to the two most common excitations. The 1D and 2D dispersion characteristics are calculated for both polarizations, showing that the TM waves undergo negative refraction in a narrow frequency band just below Wood's anomaly, whereas TE polarized waves exhibit ordinary positive refraction. Finally, possible homogenization of the fishnet metamaterial is considered, showing that only for small angles of incidence and in the immediate vicinity of Wood's anomaly can the fishnet be seen as homogenizable uniaxial medium.
Optics Express 08/2010; 18(17):17940-9. · 3.59 Impact Factor
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ABSTRACT: This paper presents a sub-nanosecond pulse transmitter of through-the-wall surveillance radar. The basis of the generator is a step recovery diode and a unique pulse-forming circuit, which forms an ultra-wideband Gaussian pulse. High amplitude pulses are advantageous for obtaining a good radar range, especially when penetrating thick and lossy building walls. In order to increase the output power of the transmitter, the outputs of two identical pulse generators were connected in parallel. A transmission line pulse forming network was then used to form an output monocycle pulse. The measurements show waveforms of the generated monocycle pulses over 33 V in amplitude.
Microwave Conference, 2009. APMC 2009. Asia Pacific; 01/2010
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ABSTRACT: This paper presents a sub-nanosecond pulse generator intended for a transmitter of through-the-wall surveillance radar. The basis of the generator is a step recovery diode, which is used to sharpen the slow rise time edge of an input driving waveform. A unique pulse shaping technique is then applied to form an ultra-wideband Gaussian pulse. A simple transistor switching circuit was used to drive this Gaussian pulser, which transforms a TTL trigger signal to a driving pulse with the timing and amplitude parameters required by the step recovery diode. The maximum pulse repetition frequency of the generator is 20 MHz. High amplitude pulses are advantageous for obtaining a good radar range, especially when penetrating thick lossy walls. In order to increase the output power of the transmitter, the outputs of two identical generators were connected in parallel. The measurement results are presented, which show waveforms of the generated Gaussian pulses approximately 180 ps in width and over 32 V in amplitude.
Microwave Conference, 2009. EuMC 2009. European; 11/2009
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ABSTRACT: It is well known that leaky waves can be found in addition to the bound wave on planar transmission lines at proper frequency ranges. This effect is documented here under the real conditions of a microstrip line of finite dimensions excited by a real source supplying finite power. The presence of these modes depends on the dimensions of the microstrip and on the frequency of the source. This paper describes an experimental verification that illustrates the existence of leaky waves on the microstrip line.
Radioelektronika, 2009. RADIOELEKTRONIKA '09. 19th International Conference; 05/2009
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ABSTRACT: This paper presents a new planar particle showing negative effective permittivity under irradiation by an electromagnetic wave. The response of this particle, aimed to be sensitive to an electric field, is strongly anisotropic. The particle is used to design an isotropic epsilon-negative metamaterial in two forms. Firstly, a unit cell of the metamaterial consists of a cube bearing six proposed particles on its faces, located with specific orientations. The experiments showed that this unit cell is suitable for manufacturing an isotropic epsilon-negative metamaterial obtained by arranging these cells in a 3D cubic periodic system. The second form of an epsilon negative metamaterial with an isotropic response consists of the proposed planar particles themselves, distributed quasi-randomly, composing a 2D system and/or of particles placed in spherical shells and distributed fully randomly in a hosting material composing a 3D system. The isotropy of these systems was verified by measurements in a rectangular waveguide.
Microwave Conference, 2008. EuMC 2008. 38th European; 12/2008
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ABSTRACT: This paper presents an experimental and theoretical study of the coupling of split ring resonators, and aims to show ways to widen the frequency band of the response of mu-negative metamaterials. The behaviour of these metamaterials is theoretically described in terms of coupled resonant circuits theory. In particular the coupling is studied on pairs of split ring resonators and systems containing the greater number of resonators. Widening of the metamaterial response frequency band is caused primarily by dispersion of the resonant frequencies of the particular resonators, and to a minor extent by mutual coupling. The more particles participate in the tested system, the wider the frequency band of the system response. The requirement to obtain an isotropic medium is taken into account.
Microwave Symposium Digest, 2008 IEEE MTT-S International; 07/2008
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ABSTRACT: This paper presents a new version of a leaky wave antenna based on a conductor-backed slotline with a stacked substrate. The advantage of this new structure is its flat top surface, due to the antenna being fed from the rear side via an SMA connector. The antenna radiates into a single main beam above the substrate. A bi-directional antenna radiating symmetrically both forwards and backwards was obtained by mirroring the structure.
Microwaves, Radar and Wireless Communications, 2008. MIKON 2008. 17th International Conference on; 06/2008
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ABSTRACT: This paper deals with reflectivity of a gold layer of nanometer-scale thickness sputtered on a dielectric foil at microwave frequencies. A model of nanometer-scale spheres characterizes the behavior of the layer. For short sputtering times, these spheres are separated, and later they touch each other to form a continuous layer. The structure is analyzed in several ways. The first model, as suggested in the literature, replaces the spheres by their electric dipole moments, while the second, newly proposed model replaces them by their mutual capacities. The structure is also being investigated by the CST Microwave Studio software. The data provided by the models is compared with the data obtained from measurements carried out and published by the authors previously. The reduction in effective conductivity of the layer due to microscopic phenomena in thin films is taken into account in the models. The measured conductivity is compared with values taken from the literature, and the differences are discussed.
IEEE Transactions on Nanotechnology 12/2007; · 2.29 Impact Factor
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ABSTRACT: In this paper a triple wire medium is described as an isotropic negative permittivity medium. A numerical experiment was performed to validate the propagation of electromagnetic waves inside the wire lattice below the plasma frequency, where the effective medium permittivity is negative. For a practical realization, a form of the triple wire medium using a planar technology was designed, fabricated and measured.
Microwave Conference, 2007. European; 11/2007
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ABSTRACT: This paper presents the application of a flat waveguide with a longitudinal slot in the middle of its wider wall for the design of a leaky wave antenna. The antenna is fed from a coaxial connector on its bottom, and provides a totally flat top surface and a radiation pattern with better suppression of side lobes than in the case of an antenna fed via a CPW patch. The antenna radiates into one relatively narrow main beam. The antenna characteristics and radiation aspects are discussed here. Its measured characteristics are in accord with those predicted by simulation.
Microwave Conference, 2007. European; 11/2007
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ABSTRACT: This paper presents two particles with negative permittivity in some frequency band. The response of a single dipole loaded by an inductance is strongly anisotropic. The response of a spider dipole does not depend on the orientation of the electric field of a wave being incident perpendicular to the particle substrate. These two particles are used in designing an isotropic epsilon-negative metamaterial. A unit cell of the metamaterial consists of a cube bearing the proposed particles on its faces, located with specific orientations. The experiments showed that only the single inductively loaded dipole is suitable for manufacturing of an isotropic epsilon-negative metamaterial. The isotropy of the new particles was checked by measurements.
Microwave Symposium, 2007. IEEE/MTT-S International; 07/2007
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ABSTRACT: In this paper a triple wire medium is described as an isotropic negative dielectric permittivity medium. A numerical experiment was performed to validate the propagation of electromagnetic waves inside the wire mesh both below and above the plasma frequency. For a practical realization, a form of the triple wire medium using a planar technology is proposed.
Radioelektronika, 2007. 17th International Conference; 05/2007
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ABSTRACT: The permittivity, permeability and conductivity of a material characterize its ability to interact with an electromagnetic field. In nature, the magnitudes of these three quantities are restricted mostly to positive values. In contrast, metamaterials are artificially produced composite media exhibiting electromagnetic responses that natural materials do not provide. They enable the three constitutive parameters to be cast down to negative values. Nowadays, electromagnetic metamaterials is a rapidly growing research domain involving electromagnetism, microwave and millimeter wave technology, optics, material technology and nanotechnology. There are prospects for many challenging practical applications. A historical survey of the evolution of metamaterials from the earliest assumptions until the current state of the art introduces discussion upon the metamaterials, description of their characteristics and behavior. Metamaterials are known in two forms. An inherent metamaterial is a real 3D solid volumetric medium. 1D or 2D planar circuits are the second version of metamaterials. The first form is characterized by field theory, while the second form utilizes transmission line theory. Manifold applications of guided waves, radiated waves, new microwave circuits, devices and structures will be discussed from the engineering point of view. There is a brief report on the authors' innovative findings. This involves both theoretical and experimental results that have been achieved in recent years. In particular, it concerns the utilization of split ring resonators in negative permeability metamaterials, the concept and the production of an isotropic negative permeability medium, an isotropic negative permittivity medium, CPW supporting propagation of a left-handed wave, and wire media exhibiting negative permittivity. Finally, prospects for further developments in this interesting field are presented.
Radioelektronika, 2007. 17th International Conference; 05/2007
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ABSTRACT: A new concept of a passive waveguide reflection attenuator and a T-junction with a variable ratio of the output powers is reported here. A conductive uniform linear polarization grid of nano thickness is inserted into the standard rectangular waveguide. Rotation of the grid results in a change of the output powers. The measured scattering matrix elements compare well with the computer simulation, confirming the expected characteristics of the two circuits.
Microwave Conference, 2006. APMC 2006. Asia-Pacific; 01/2007
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ABSTRACT: A new concept of passive waveguide circuits is presented. It is based on a combination of the standard rectangular waveguide with a metal uniform linear polarization grid of nano thickness. The grid is deposited on a polymer foil and inserted into the waveguide, allowing it to rotate between two opposite flanges. The concept is demonstrated on a T-junction with an adjustable ratio of the output powers, and on a variable reflection attenuator. The two circuits were designed, manufactured and tested. The measured characteristics compare well with the computer simulations, and have confirmed the expected behavior of the two circuits
Microwave Conference, 2006. 36th European; 10/2006
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ABSTRACT: This paper presents the application of a flat waveguide with a longitudinal slot in the middle of its wider wall for the design of a leaky wave antenna. The antenna radiates into one relatively narrow main beam and its gain is 14.2 dB at 4.75 GHz. The characteristics and radiation aspects of the antenna are discussed. The measured antenna characteristics are in accord with those predicted by simulation
Microwave Symposium Digest, 2006. IEEE MTT-S International; 07/2006
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ABSTRACT: This paper presents the results of an investigation of a thin layer of gold sputtered on a dielectric foil. This layer is modeled by nanometer-scale spherical particles that are separated at short deposition times and later touch each other, forming a continuous layer. Four ways of analyzing the structure are introduced. The first method describes the spheres by their electric dipole moment, while the second, newly proposed method, takes into account the capacity between adjacent spheres, and the third method assumes the layer as homogeneous and considers its reduced conductivity due to the behavior of electrons in thin films. The CST microwave studio model, which takes into account the random distribution of particles, offers the reflection coefficient that best fits measured data.
Microwaves, Radar & Wireless Communications, 2006. MIKON 2006. International Conference on; 06/2006
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ABSTRACT: The design, analysis, fabrication and measurement of a new bulk metamaterial is reported in this paper. The structure of the new medium is made up of left-handed parallel strips. The series capacitors are realized by short circuited parallel strip stubs, and the conducting shunt pins represent parallel inductors. This metamaterial allows the propagation of a left-handed wave in the frequency band from 4.75 to 5.65 GHz, much wider than the frequency band achievable by split-ring resonators. The simple equivalent circuit of the metamaterial is derived. Additional modification of the media structure is proposed.
Microwave Conference, 2005 European; 11/2005
