Advanced Electromagnetics (E-Journal)
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Application of the Shifted Frequency Internal Equivalence to Two Dimensional Lossy Objects
No full textPerformance of a new method, Shifted Frequency Internal Equivalence (SFIE) is studied in the analysis of scattering from two dimensional lossy objects. This method finds the solution of a wideband scattering problem faster than classical approaches.By introducing conductivity, loss shows itself as imaginary electrical permittivity. Changing conductivity also changes the distribution of electromagnetic waves and modifies RCS plots. In this study homogeneous and inhomogeneous conductive media are investigated to widen the usage of SFIE method. By increasing conductivity skin effect phenomenon is observed, electrical dimensions are decreased and RCS plots are flattened as expected.Numerical results obtained by SFIE are compared to the ones obtained by Method of Moments and the differences are shown
Design and Characterization of a Compact Single Layer Modified S-Shaped Tag Antenna for UHF-RFID Applications
No full textIn this paper, we report the design of a new compact single layer modified S-shaped tag antenna for UHF-RFID applications. To achieve a compact size of 51×34 mm2 for this tag antenna, the technique of using S shaped strip is applied, and by further adding a pair of equilateral triangular stubs into this structure, good impedance matching can be obtained at 915 MHz, which is the center frequency of the North-American UHF-RFID band (902 to 928 MHz). Besides exhibiting acceptable 5m read range in free space at 915 MHz, the proposed design shows a read range of about 4.5 when mounted on a metallic object (200 ×30 cm2) separated by spacer foam of thickness 1 cm. Furthermore, the proposed design shows a reasonable read ranges when it is mounted on different dielectrics with low permittivity. The proposed design has a simple configuration, low cost, acceptable read range, and can work on various background materials.  
Numerical Method for Electromagnetic Wave Propagation Problem in a Cylindrical Anisotropic Waveguide with Longitudinal Magnetization
No full textThe propagation of monochromatic electromagnetic waves in metal circular cylindrical dielectric waveguide with longitudinal magnetization filled with anisotropic inhomogeneous waveguide is considered. The physical problem is reduced to solving a transmission eigenvalue problem for a system of ordinary differential equations. Spectral parameters of the problem are propagation constants of the waveguide. Numerical results are obtained using a modification of the projecting methods. The comparison with known exact solutions (for particular values of parameters) are made
High Gain Circularly Polarized Pentagonal Microstrip for Massive MIMO Base Station
No full textIn this paper we propose a circularly polarized pentagonal microstrip antenna on a suspended substrate with coaxial probe feed and five loaded slits for Massive MIMO BS Antenna applications. Massive Multiple-Input Multiple-Output (MIMO) is one of the key component to be incorporated in the 5G cellular systems. The proposed antenna is successfully simulated using HFSS 13.0, fabricated on a FR-4 substrate and measured. The proposed antenna exhibits a much higher gain of 6.17dB, improved impedance bandwidth of 171.9 MHz (Return loss, S11= -10dB) , axial ratio bandwidth (< 3dB) of 135 MHz , patch area of 1775 mm2 , and also yields return loss better than -15 dB around the center frequency of 2.45 GHz (ISM Band). Measured characteristics of the antenna are in good agreement with the simulated results
Study of Stacked High Tc Superconducting Circular Disk Microstrip Antenna in Multilayered Substrate Containing Isotropic and/or Uniaxial Anisotropic Materials
No full textIn this paper, we present a rigorous full-wave analysis able to estimate exactly the resonant characteristics of stacked high Tc superconducting circular disk microstrip antenna. The superconducting patches are assumed to be embedded in a multilayered substrate containing isotropic and/or uniaxial anisotropic materials (the analysis is valid for an arbitrary number of layers). London’s equations and the two-fluid model of Gorter and Casimir are used in the calculation of the complex surface impedance of the superconducting circular disks. Numerical results are presented for a single layer structure as well as for two stacked circular disks fabricated on a double-layered substrate
Artificial Chiral Media Using Conical-Coil Wire Inclusions
No full textThe electromagnetic response of the electrically small conical wire coil as a chiral inclusion is described. An existing model of the helical coil wire inclusion is extended to model the conical coil wire inclusion, using the Method of Moments (MoM) to determine the dominant resonant circuit impedance of the inclusion. Material parameters are determined using mixing relations with polarizability coefficients expressed for the conical coil inclusion geometry. The polarization conversion of a dielectric slab loaded with conical coil inclusions is predicted and compared to simulated results using a forward scattering technique
Light-Controlled Polarization of MM-Waves with Photo-Excited Gratings in a Resonant Semiconductor Slab
No full textWe investigated photoconductive gratings in the resonant semiconductor layers as light-controlled polarizers for the millimeter (MM) waves. We compared the effects of strip-like, wire-like, and fin-like gratings excited by the red light and the IR radiation in Silicon wafers, respectively. The fin-like gratings are shown to be the preferred structures that can operate at the limited light intensity. The light-sensitive shift of maxima of transmitted power and polarizing efficiency towards the lower frequency band is observed. The effect makes photoconductive gratings and similar patterns potentially suitable for the design of light-controlled frequency-tuning and frequency-modulating components of resonant quasi-optical devices
Microstrip Antenna Design with Circular Patch for Skin Cancer Detection
No full textDue to the many advantages of microstrip patch antennas, nowadays, microstrip patch antennas are mostly preferred in biomedical areas. This study aims two antenna structures, as both transceiver and receiver, have same dimensions are designed to produce solution of the difficulties in pathology. For antennas with an operating frequency of 2.45 GHz, FR-4 substrate material with a value of 4.4 dielectrics is used. A model has been prepared to detect the presence of skin cancer with the designed antennas. The model is a method of determining E-field and scattering parameters differences between two antennas of cancerous and normal tissue specimens placed on the glass slides. The same antennas and experimental setup were prepared with the normal and cancerous structure of the skin tissue prepared by pathologists. Thus, scattering parameters are measured and their differences are determined. It has been shown that cancerous tissue can be determined with different values obtained as a result. Ansys HFSS program is used for designs and simulations
Mutual Coupling Reduction of DRA for MIMO Applications
No full textIn this paper, A multiple input Multiple Output (MIMO) antenna using two Square Dielectric Resonators (SDRs) is introduced. The mutual coupling between the two SDRAs is reduced using two different methods; the first method is based on splitting a spiral slot in the ground plane, then filling the slot with dielectric material, "E.=2.2". The second method is based on inserting a copper parasitic element, having the same shape of the splitted Spiral, between the two SDRAs. The effect of replacing the copper parasitic element with Carbon nanotubes (CNTs) parasitic element "SOC12 doped long-MWCNT BP" is also studied. The antenna system is designed to operate at 6 GHz. The analysis and simulations are carried out using finite element method (FEM). The defected ground plane method gives a maximum isolation of l8dB at element spacing of 30mm (0.6λo), whereas the parasitic element method gives a maximum isolation of 42.5dB at the same element spacing
Characterization of Transmission and Reflection of Ku Band Split Ring Resonator Reflectarray using Waveguide Method
No full textIn this paper, the analysis, design, and measurement of a split ring resonator reflectarray is presented. The 6 different designs of reflectarray are simulated to analyze the effect of splits position on resonance frequency. The SRR reflectarray which covered highest frequency bandwidth at Ku-band is fabricated and tested. In the fabrication, FR4 substrate is used. The S-parameter measurements of the fabricated reflectarray are performed by waveguide method. The obtained results have good reflection characteristics for a wide frequency range from 12 GHz to 16.5 GHz in Ku-band. The maximum value of reflection is achieved approximately at 15.3 GHz frequenc