Acessibilidade / Reportar erro
Journal of Microwaves, Optoelectronics and Electromagnetic Applications, Volume: 17, Número: 3, Publicado: 2018
  • Modeling of Open Square Bifilar Planar Spiral Coils Article

    Silva, Denivaldo P. da; Pichorim, Sérgio F.

    Resumo em Inglês:

    Abstract In this paper an electrical model for square bifilar planar spiral coils (BPSC) is presented. Its main aim is the study of BPSC electrical parameters and behavior involving the frequency range where the first resonances (valley and peak) occur for bifilar coils in open-circuit configuration. A new approach to determine mutual capacitances of BPSCs based on coplanar waveguide (CPW) lines is presented. This study can be applied for modeling of passive self-resonant (PSR) sensors and wireless power transfer (WPT) systems. In order to validate the proposed model, three BPSCs were manufactured, tested by means of an impedance analyzer and also submitted to electromagnetic (EM) simulations. The results obtained, presented by means of tables and graphs, show that the present study is feasible and promising for the modeling of open square BPSCs.
  • Single Band Notched Characteristics UWB Antenna using a Cylindrical Dielectric Resonator and U-shaped Slot Article

    DEBAB, Mohamed; MAHDJOUB, Zoubir

    Resumo em Inglês:

    Abstract In this manuscript, a novel hybrid dielectric resonator antenna for ultra wideband (UWB) applications is designed, and single band notched performance is proposed. The circle radiating patch is printed on the FR4 substrate of 1.64 mm thickness and loss tangent tan δ =0.02, and is fed by the coplanar waveguide. The size of the UWB antenna was minimised to 50-40 mm2. The cylindrical dielectric resonator (CDR) was used to broaden the bandwidth and achieve an impedance bandwidth of more than 113%, covering a frequency range of 3.3 to more than 12GHz. WIMAX band notched characteristics of the antenna to reject (3.2-3.8GHz) were realised by etching a U-shaped slot in the radiating patch. The centre notch frequency can be adjusted from 3.4 to 4.5 GHz by changing the position of the CDR. The band notched characteristics, VSWR, and radiation patterns were studied using the CST microwave simulator and confirmed with the frequency domain ANSOFT high frequency structure simulator (HFSS).
  • Beampattern Synthesis for Frequency Diverse Array Based on Time-Modulated Double Parameters Approach Article

    Mu, Tong; Song, Yaoliang; Wang, Zhonghan

    Resumo em Inglês:

    Abstract The basic frequency diverse array (FDA) using linearly increasing frequency increments generates a range-angle dependent beampattern. However, it is coupled in range and angle dimensions and is also periodic in range and time, making its applications limited. In this paper, a novel FDA beampattern synthesis approach is proposed utilizing the time-modulated double parameters based on the chaos sequence. The chirp signal mechanism is used instead of the single-frequency signal mechanism. Meanwhile, the multi-carrier architecture is used for range-angle decoupling. Satisfactory time-invariant range-angle beampattern can be synthesized for both single and multiple targets locations. Simulation results show the effectiveness of the proposed FDA scheme. Furthermore, comparative study with the existing technology indicates that the proposed approach can provide better performance in spatial focusing and side-lobe suppressing.
  • The Behavior of CPW-Fed Sierpinski Curve Fractal Antenna Article

    Reha, Abdelati; El Amri, Abdelkebir; Bouchouirbat, Marouane

    Resumo em Inglês:

    Abstract In this paper, the behavior of Coplanar Waveguide (CPW) fed SIERPINSKI curve fractal antenna is studied. The results show that there is a relationship between the iteration number and the resonance frequencies. With increase in the number of iteration the resonance frequency decreases with a constant ratio. The use of fractal structures to design antennas makes them more miniaturized. The simulated results obtained from CADFEKO a Method of Moments (MoM) model based Solver and measurement using Vector Network Analyzer Anritsu MS2026C are in good agreement.
  • Application of the Finite-Difference Frequency-Domain (FDFD) method on radiowave propagation in urban environments Article

    Batista, Cláudio Garcia; Rego, Cássio Gonçalves do

    Resumo em Inglês:

    Abstract In this work a Finite-Difference Frequency-Domain (FDFD) propagation method for complex urban environments is proposed. The formulation starts from the discretization of the Helmholtz equation for the magnetic field instead of the usual separate one order derivative Ampere's and Faraday's laws. The Stretched Coordinate Perfectly Matched Layer (SCPML) is used as an absorbing boundary condition. These procedures produce less field components to estimate and achieve high wave absorption at the computation domain boundaries. The main goal is the rigorous prediction of VHF/SHF signals in real urban scenarios through the evaluation of several propagation mechanisms: direct rays, diffraction, reflection and refraction effects. The method is validated through an analytic problem and preliminary results are generated by two case studies: a cellular system measurement campaign and an idealized urban scenario.
  • A Review of Ground Penetrating Radar Antenna Design and Optimization Article

    Travassos, X. L.; Avila, S. L.; Adriano, R. L. da S.; Ida, N.

    Resumo em Inglês:

    Abstract Ground Penetrating Radar is a complex nondestructive evaluation technique where the antenna is the most critical part. The antenna is responsible for transmission and reception of waves at the proper level and frequencies defined in the GPR system specifications. Important GPR features such as resolution and penetration depth depend on its characteristics. In this context, this work outlines the fundamental GPR system theory in order to discuss procedures for improving antennas to GPR applications. Additionally, recent works regarding GPR antenna optimization are reviewed and placed in the context of a framework for GPR antenna design and optimization.
  • Design Equations for Spiral and Scalable Cross Inductors on 0.35 μm CMOS Technology Article

    Fontebasso Neto, José; Moreira, Luiz Carlos; Correra, Fatima Salete

    Resumo em Inglês:

    Abstract This paper presents a set of design equations for spiral and new scalable cross inductors in CMOS 0.35 μm technology, relating electrical parameters of the inductor's equivalent circuit as functions of its geometric dimensions. The procedure used to derive the design equations is described and involves electromagnetic simulation of inductors with different geometric dimensions, extraction of values for equivalent circuit model elements for each inductor and the use of multivariate regression analysis applied to generalized linear models (GLM) based on Design of Experiments (DoE). A nine element π-type equivalent electrical circuit was used for the inductors, where all element values are constants, allowing simulation on SPICE-like software. Results from the models obtained for both spiral and scalable cross inductors presented closely match to the simulated results.
Sociedade Brasileira de Microondas e Optoeletrônica e Sociedade Brasileira de Eletromagnetismo Praça Mauá, n°1, 09580-900 São Caetano do Sul - S. Paulo/Brasil, Tel./Fax: (55 11) 4238 8988 - São Caetano do Sul - SP - Brazil
E-mail: editor_jmoe@sbmo.org.br