Papers by Keyword: Waveguide

Abstract: Combined coaxial-circular waveguide equipped with protective module allowing the transmission of microwave energy of three magnetrons with the output of 0.9 kW per each into the pressurized reaction chamber and capable of operating at temperatures of up to 250 °C and a pressure of up to 10 bars was designed and tested. Choke flange junction of the waveguide sections was used instead of contact flange connection. The developed waveguide construction allows to place the radio transparent partition inside the free space volume of a choke flange junction performing protection of emitters and summing of microwave energy of three magnetrons with an efficiency close to 100% that was proven by tests with fresh water as a microwave energy absorber. The extraction set-up equipped with the above-mentioned waveguide has demonstrated the stable and safety operation of the transmitting block and the accurate automatic control of the temperature and pressure inside the reaction chamber in the presence of a strong electromagnetic field. The construction of the microwave extraction set-up allows to use the impact of the combination of temperature and pressure on the cell wall, promoting the high rate isolation of secondary metabolites from biomass that was demonstrated by water extraction of black alder bark.

Abstract: We applied the dielectric function method to solve analytically L-NL-L structure problems with negative Kerr nonlinearity. A damped wave in linear and a periodic standing wave in non-linear media had to be matched at boundaries. We gave a formulation of boundary conditions that did not explicitly include a film thickness. The boundary-value of a dielectric function can be expressed through the constant of non-trivial integral of motion. Using it, one generates a family of matched solutions satisfying boundary conditions. Then arbitrary film thickness can be checked against this family of solutions in search of matches. As a result, all fitted solutions are determined straightforwardly.

Abstract: The possibility of obtaining multilayer cylindrical waveguides by explosion welding is investigated. The fact that the technological welding scheme has a significant impact on the shaping of workpieces and the value of edge effects was established. The studies demonstrated that the nature of wave formation during the manufacture of multilayer cylindrical waveguides from a homogeneous material by explosion welding using a central rod is identical to the wave formation when welding flat multilayer compositions on a rigid base.

Abstract: The results of a study of the influence of shapes of samples, as well as the presence of internal cavities and their shapes, on the nature of wave strain hardening (WSH) are presented. The peculiarity of the method lies in the impact of a stream of pulses on the processed material, while instant wave states, which affect the microhardness maps in the workpiece are formed in the material. These studies were carried out for the first time on a specially designed stand. The studied grades of materials were: steel 45 and bronze BRAZH 9-4. As a result of the studies performed, the geometric shape of the samples and cavities in them was revealed, which contribute to an increase in microhardness.

Abstract: Undoped and indium (In) doped TiO₂ thin films were deposited by sol-gel method onto glass substrates. Structural, optical and electrical properties of films were studied. X-rays diffraction patterns showed that the TiO₂ films consist of anatase phase. AFM images revealed that the surface roughness of In:TiO₂ films is smoother than that of undoped TiO₂ films. UV–Vis transmittance results showed TiO₂ films have significant optical absorption in the region of 300–350 nm and are fully transparent in the visible. Both film thickness and refraction index in dependence on the fraction of In doping are derived from TE and TM optical guided modes excited in a prism coupler. The optical gap E_g decreases from 3.50 eV for undoped TiO₂ film to 3.43 eV at 2 at.% In doping and then increases for doping with indium at 10 at.%. The electrical characterization shows a maximum electrical conductivity of 2.7 (S/cm) obtained for the film doped with 10 at.% In.

Abstract: In this thesis, the RF front-end was done at K/Ka (18-27 GHz/26.5-40 GHz) bands used for satellite communication and satellite TV [1]. In this study, vertical polarized signal transmission and horizontal polarized signal reception were performed. The design is set to be compatible with TURKSAT 4B [2]. RF front-end is consist of an offset dish providing high gain and low side lobe level (SLL) for collecting the signal, a circular horn antenna which is compatible with RHCP (Right Hand Circular Polarization) and LHCP (Left Hand Circular Polarization) polarizations at the focal point of the dish, to separate dual polarization an orthomode transducer (OMT) and a transmit reject filter to prevent the receiver from the strong signal generated at the transmitter side (cross-pol). In the design waveguide structures is used to work in microwave frequencies and for high power delivery requirements. AWR Microwave Office, Computer Simulation Technology (CST) and MATLAB (Matrix Laboratory) programs are used for simulation, optimization and calculations.

Abstract: — Barium titanate (BaTiO₃) thin films are suitable for many application especially photonics. BaTiO₃ thin films are deposited using spin coating with an optimum spin speed of 4500rpm. The samples are then characterized using XRD, AFM and SEM. The results of the XRD analysis showed that both the 5-and 10-coated layers are polycrystalline BaTiO₃ with differences in terms of diffraction intensity, due to the number of layers. As for optical application, the surface roughness is the most crucial part. The number of layers of 5 and 10 have thickness of 2.927nm and 4.456nm RMS.

Abstract: The compressor contains the oversized cylindrical cavity with two interference output units each in the figure of a circular waveguide H-tee. The H-tees are coupled by a waveguide section and the energy is extracted synchronously through two output ports. The synchronism is provided through using a single microwave switch mutual for both H-tees. Simulation and experimental study of the X-band microwave compressor were carried out. The simulation made it possible to optimize the configuration of the oversized storage cavity and the output element. The amplification factor was 14 dB when the energy was extracted though one output unit at the output pulsewidth of 6...7 ns. Amplification factor and the output power were increased by 2dB and the pulsewidth was decreased down to 3...3.5 ns when the energy was extracted synchronously through two output units.

Abstract: The effective numerical aperture calculation in two-dimensional Photonic crystal waveguide has been proposed. In this paper we present the analysis of ray optics refracted inside nanorods and at the boundaries between rods, which separates rod gap is much smaller than the incident wavelength assumed to reflect on the region. In operation, the resolving numerical aperture was compared with the finite difference time domain method via OptiFDTD software. Although numerical aperture mentioned above was found to be extremely close to fiber optics, a transmission passes though compartments of the rods are observed due to significant estimation of transmission and reflection of electric field. The compared simulation results will be discussed. By the aforementioned is that in the near future we will modify wave equation in periodic media of waveguide structures reached to the transverse electric equation of beam propagation in the two-dimensional Photonic crystal waveguide analysed.

Abstract: Conventional plasmonic devices involve metals, but metal-based plasmonic resonances are mainly limited to λ_res < 1 μm, and thus metals interact effectively only with light in the UV and visible ranges. We show that highly doped ZnO can exhibit λ_res ≥ 1 μm, thus moving plasmonics into the IR range. We illustrate this capability with a set of thin (d = 25–147 nm) Al-doped ZnO (AZO) layers grown by RF sputtering on quartz glass. These samples employ a unique, 20-nm-thick, ZnON buffer layer, which minimizes the strong thickness dependence of mobility (μ) on thickness (d). A practical waveguide structure, using these measurements, is simulated with COMSOL Multiphysics software over a mid-IR wavelength range of 4–10 μm, with a detailed examination of propagation loss and plasmon confinement dimension. In many cases, L_plas < λ_light, thus showing that IR light can be manipulated in semiconductor materials at dimensions below the diffraction limit.