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Physics of Metamaterials
Láska, Martin ; Kalousek, Radek (referee) ; Dub, Petr (advisor)
The bachelor work deals with electrodynamics of metamaterials for which both the electric permittivity and magnetic permeability are simultaneously negative. It is shown that the double negative media are described by a negative refraction index which has an important impact on optics laws. In particular, the negative refraction is demonstrated by simulation of interaction of the Gauss monochromatic beam impinging on a negative refractive material. Next, the electromagnetic energy propagation in the negative refractive materials is studied. It is shown that the energy propagation velocity equals the group velocity, which has the opposite sign than the phase velocity. Finally, Fresnel formulas valid both for positive and negative refraction index are given.
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A Brief Design of Optical Resonators
Hubík, Daniel ; Nešpor, Dušan (referee) ; Kadlec, Radim (advisor)
This bachelor thesis is focused on analysis of split-ring resonators in THz region. Simulations were made by finite elements method and by finite-difference time-domain method. At first we created a resonating structure that works in GHz region. Then we were observing a dependence of movement of resonant frequency on the size of resonator. In the final chapter we assigned frequency dependent values of permitivity to such structure. As the result we simulated working resonator at frequency 500THz. All simulations have been made in program HFSS ANSYS and Lumerical FDTD Solutions.
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Effect of polymer type on the properties of 3D printed auxetic structures
Zbíral, Roman ; Štaffová, Martina (referee) ; Jančář, Josef (advisor)
This thesis deals with special structures such as optical, acoustic and mechanic metamaterials, which has their own specific properties. Auxetic materials as subgroup of mechanical metamaterials has its own special arrangement of sub-cells, that is bound to negative Poisson’s ratio. With mechanical load auxetic materials change its own density, geometry of structure and in thrust only change its internal structure instead of breaking. Most of these materials are made using additive technologies such as 3D print which allows better quality of produced structure and are made of special polymers which provide expected properties.
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Broad-spectrum signal propagation through inhomogeneous medium
Měcháček, Radek ; Drexler, Petr (referee) ; Fiala, Pavel (advisor)
Work is focused on both theoretical knowledge of the electromagnetic field and the specific properties of metamaterials measured. First, be informed about the fundamentals of electromagnetic fields, the issue of periodic structures to the properties required metastructures. Further experimental work is designed to measure the properties of metamaterials. The measurements will be used as harmonic signals and broadband signals in the frequency range 100MHz to 10GHz. In the last part of the proposed work is carried out experimental work and are evaluated some characteristics of the antennas and measurement of the selected sample.
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Magneto-optical study of the dynamic properties of magnetic nanostructures and nanostructured metamaterials
Flajšman, Lukáš ; Chumak, Andrii (referee) ; Revelosona, Dafiné (referee) ; Spousta, Jiří (advisor)
Magnonika je novým odvětvím výzkumu, který se zabývá fyzikou spinových vln. Magnonika jako vědní obor nabízí nové možnosti například v nediskrétních výpočtech na základě vlnového charakteru spinových vln. Při výrobě magnonických prvků klasickými metodami není možné příliš měnit charakter materiálů, ze kterých jsou jednotlivé prvky vyrobeny. Tento fakt silně omezuje univerzálnost vyrobených struktur. Cílem této práce je aplikovat nový typ materiálu do oboru magnoniky. Specifikum daného materiálu je možnost zápisu magnetických struktur pomocí iontového svazku. Ukazuje se, že tyto struktury mají velice zajímavé magnetické vlastnosti, které lze velice přesně řídit právě strategií ozařování iontovým svazkem. Na základě fázově rozlišené Brillouinovy spektroskopie jsme získali disperzní relaci spinových vln v tomto systému a tím i důležité parametry systému. Pozorování podkládáme mikromagnetickými simulacemi a analytickými modely. Vlastnosti systému pro magnonické aplikace prezentujeme na třech prototypických sadách struktur, které nelze vyrobit pomocí klasických materiálů.
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Effects of material and 3D printing technology on the properties of auxetic structures
Kuchtová, Štěpánka ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
This thesis deals with the behaviour of auxetic structures. In particular, the focus is on the effect of the 3D printer, material filament and number of unit cells on the deformation response of auxetics. Specimens were prepared on two printers with a direct and a bowden extruder made of PET-G (polyethylene terephthalate glycol) and TPU (thermoplastic polyether polyurethane) materials. The prepared structures were subjected to a static compression test, during which video recordings were taken. From the video recordings the Poisson's ratio and porosity of the samples were subsequently evaluated. A software application was written in Python programming language to evaluate the Poisson's ratio and porosity. The type of 3D printer had a significant effect on the properties of the prepared auxetic structures. The specimens prepared by the bowden extruder printer exhibited lower stiffness and yield strength and higher Poisson's ratio compared to the samples prepared by the direct extruder printer. Furthermore, the influence of the number of unit cells and influence of the material with low (TPU) and high (PET-G) elastic modulus on the auxetic behaviour was investigated. In the case of the flexible material, specimens with fewer unit cells exhibited tougher response, whereas the opposite was true for PET-G. At the same time, attention was paid to the deformation response of single cells within the sample, where TPU exhibited a different deformation behaviour mechanism than PET-G. This has been reflected in different spatial distribution of auxetic behaviour within the specimens.
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Effect of polymer type on the properties of 3D printed auxetic structures
Zbíral, Roman ; Štaffová, Martina (referee) ; Jančář, Josef (advisor)
This thesis deals with special structures such as optical, acoustic and mechanic metamaterials, which has their own specific properties. Auxetic materials as subgroup of mechanical metamaterials has its own special arrangement of sub-cells, that is bound to negative Poisson’s ratio. With mechanical load auxetic materials change its own density, geometry of structure and in thrust only change its internal structure instead of breaking. Most of these materials are made using additive technologies such as 3D print which allows better quality of produced structure and are made of special polymers which provide expected properties.
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Magneto-optical study of the dynamic properties of magnetic nanostructures and nanostructured metamaterials
Flajšman, Lukáš ; Chumak, Andrii (referee) ; Revelosona, Dafiné (referee) ; Spousta, Jiří (advisor)
Magnonika je novým odvětvím výzkumu, který se zabývá fyzikou spinových vln. Magnonika jako vědní obor nabízí nové možnosti například v nediskrétních výpočtech na základě vlnového charakteru spinových vln. Při výrobě magnonických prvků klasickými metodami není možné příliš měnit charakter materiálů, ze kterých jsou jednotlivé prvky vyrobeny. Tento fakt silně omezuje univerzálnost vyrobených struktur. Cílem této práce je aplikovat nový typ materiálu do oboru magnoniky. Specifikum daného materiálu je možnost zápisu magnetických struktur pomocí iontového svazku. Ukazuje se, že tyto struktury mají velice zajímavé magnetické vlastnosti, které lze velice přesně řídit právě strategií ozařování iontovým svazkem. Na základě fázově rozlišené Brillouinovy spektroskopie jsme získali disperzní relaci spinových vln v tomto systému a tím i důležité parametry systému. Pozorování podkládáme mikromagnetickými simulacemi a analytickými modely. Vlastnosti systému pro magnonické aplikace prezentujeme na třech prototypických sadách struktur, které nelze vyrobit pomocí klasických materiálů.
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A Brief Design of Optical Resonators
Hubík, Daniel ; Nešpor, Dušan (referee) ; Kadlec, Radim (advisor)
This bachelor thesis is focused on analysis of split-ring resonators in THz region. Simulations were made by finite elements method and by finite-difference time-domain method. At first we created a resonating structure that works in GHz region. Then we were observing a dependence of movement of resonant frequency on the size of resonator. In the final chapter we assigned frequency dependent values of permitivity to such structure. As the result we simulated working resonator at frequency 500THz. All simulations have been made in program HFSS ANSYS and Lumerical FDTD Solutions.
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Broad-spectrum signal propagation through inhomogeneous medium
Měcháček, Radek ; Drexler, Petr (referee) ; Fiala, Pavel (advisor)
Work is focused on both theoretical knowledge of the electromagnetic field and the specific properties of metamaterials measured. First, be informed about the fundamentals of electromagnetic fields, the issue of periodic structures to the properties required metastructures. Further experimental work is designed to measure the properties of metamaterials. The measurements will be used as harmonic signals and broadband signals in the frequency range 100MHz to 10GHz. In the last part of the proposed work is carried out experimental work and are evaluated some characteristics of the antennas and measurement of the selected sample.
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