Humberto Cesar Chaves Fernandes

Attenuation and propagation in various finline structures

The theory and numerical results of the asymmetric single and coupled bilateral and unilateral finlines and arbitrary antipodal finline considering the attenuation of the substrate are presented. Results are given to the complex propagation constant. The full wave analysis of the Transverse Transmission Line — TTL method is used in the FTD. Applying the moment method the complex propagation constant, including the attenuation constant and the phase constant, are obtained. The effective dielectric constant, ɛeff,, and the characteristic impedance are also calculated. The results are compared with the references, and news results are presented for these parameters.

Analysis of antennas with PBG substrate

The use of photonic materials has been used in the theory of optical waves. The PBG (Photonic Band Gap) theory and material, was developed recently for optical frequencies and can be easily applied to millimeter waves, microwaves and planar antenna frequencies. The presence of photonic materials as substrate in antennas has some good characteristics such as, supression of light spontaneous emission and suppression of surface waves, allowing the application in planar antenna array. In this work an elaborate analysis using the full wave Transverse Transmission Line - TTL method, that provides efficient and concise results is applied to the planar antennas array with PBG substrate.

High precision analysis of finlines on semiconductor substrate

In this study, the effect of the metallization thickness in finlines on semiconcuctor substrate is researched. The propagation parameters are computed to measure the inluence of the metallization. The theory and numerical results are presented to the propagation constant and characteristic impedance of the bilateral and unilateral finlines. The full wave analysis of the transverse transmission line — TTL method is used to determine the electromagnetic fields of the structure in Fourier transform domain — FTD. Applying the suitable boundary conditions, the moment method and expanding the fields in a set of suitable bases functions, a homogeneous matrix system is obtained and the propagation constant is computed. The characteristic impedance is obtained using the relation of the voltage in the slot and the transmitted power by the structure.Computational programs are developed to obtain numerical results to the propagation parameters composed by the propagation constant and characteristic impedance.

Coupling analysis at the coupler and edge-coupled unilateral fin line

Computer programs are developed in FORTRAN 77 and Matlab for Windows languages, given the results in 3-D of the dispersion and of the coupling, as functions of the frequency, conductivity and permittivity for the unilateral fin lines coupler asymmetric in E-plane, on semiconductor substrate. The characteristic impedance and complex propagation constant, for the odd and even-modes excitation are obtained by Transverse Transmission Line method -- TTL. These programs are easily used in graduate and undergraduate courses with good efficiency.

Shielded and open two-layer superconducting microstrip lines

The full wave analysis in the spectral domain of the Transverse Transmission Line (TTL) is used in the analysis of the shielded and open two layers microstrip lines considering the superconductor strip and semiconductor substrate. The superconductor effect is included with the boundary condition of the surface impedance that is calculated from an advanced two-fluid model. Considering that the thickness of the strip is more thin than the penetration depth, the surface current and the fields within the strip are approximately uniforms. For a substrate with high permitivity, the density of current will be practically equal to current in the bottom of the strip. Applying the Moment method is obtained the homogeneous matrix system, and the complex root of the characteristic matrix is the complex propagation constant of the structure, including the phase constant and the attenuation constant. Results are presented for the complex propagation constant, of the shielded and open two layers superconducting microstrip lines versus the frequency and the temperature, where the effects of the material superconductor are shown.

METALLIZATION THICKNESS IN BILATERAL AND UNILATERAL FINLINES

The theory and numerical results are presented to the effective dielectric constant and characteristic impedance of bilateral and unilateral finlines with metallization thickness. The full wave analysis of the transverse transmission line — TTL method is used to determine the electromagnetic fields of the structure in Fourier transform domain — FTD. Applying the suitable boundary conditions and the moment method, a homogeneous matrix system is obtained and the effective dielectric constant is extracted. The characteristic impedance is obtained using the relation between the voltage in slot and the transmitted power.Computational programs are developed to obtain numerical results to the effective dielectric constant and characteristic impedance.

Antenna for Fifth Generation (5G) Using a EBG Structure

Currently, there is a breakthrough in wireless networks - Wi-Fi - but also in studies on the optimization of antennas. This article was developed with the purpose of presenting an antenna applied for fifth generation (5G), operating at frequency of 28 GHz, using an EBG (Electromagnetic Band Gap) structure to obtain an increased bandwidth. With faster speed, lower latency and performance significantly greater than any other, shows up the internet of the future. The proposed antenna uses, as substrate, RT5880, Rogers Corporation, with 2.2 and relative permittivity of 0.009 loss tangent and multi-cylinder drilled in the ground plan of radius of 0.2 mm. Is not required no drilling in the substrate. To obtain the results, simulations and analysis of the structure under study was used the HFSS TM program (High Frequency Structural Simulator). In view of the good results this antenna can be considered a good candidate for applications in 5G.

Dynamic analysis of superconductor at high temperature for antennas array

The analysis and new results of the resonance frequency and radiation pattern of antennas array, for glass fiber FR-4 substrate using superconductor and copper patch, are presented. The linear superconducting rectangular antennas array uses the new materials SnBaCaCuOy at temperature of 160 K with conductivity equal 1.5 x 105 S/m. The concise full wave Transverse Transmission Line (TTL) method is used in the analysis and to obtain some results. The HFSS is also used and new results for the reflection coefficient (S11), return loss as functions of the resonant frequency, and pattern radiation of antennas array, are presented.

Black Box Model of Erbium-Doped Fiber Amplifiers in C and L Bands

In this paper we analyze Gain and Noise Figure of a C and an L band EDFA verifying experimentally the behavior of the involved parameters as a function of the power and the wavelength.

Microstrip Array with PBG Substrate

The phased array formed by microstrip antennas is analyzed using the full wave Transverse Transmission Line (TTL) method. For the microstrip patch resonator a set of equations that represents the electromagnetic fields in the x and z directions as function of the fields in the y direction are obtained applying the TTL method. The structure PBG (Photonic Band Gap) is analyzed using the homogenization theory, the objective is obtain the equivalent permittivity of structure. Numerical results of the radiation pattern for some phase excitation in a phased array are shown.