Gain properties of an axially slotted cylinder with two coating layers

2015 ◽  
Vol 8 (7) ◽  
pp. 1061-1068 ◽  
Author(s):  
Zeeshan Akbar Awan
Keyword(s):  
Outer Layer ◽  
Free Space ◽  
Relative Permittivity ◽  
Forward Direction ◽  
Negative Type ◽  
Different Types ◽  
Magnetic Type ◽  
Negative Materials ◽  
Coating Layers ◽  
Negative Medium

The gain properties of an axially slotted cylinder coated with two lossless layers and embedded in a certain lossless background medium have been investigated analytically. The effects of different types of coating layers, i.e. dielectric, magnetic, and Single Negative materials upon the gain characteristics of an axial slot have been discussed. It is observed that if inner layer is either of dielectric or magnetic type and outer layer is an Epsilon Negative type having its relative permittivity of negative one and slotted cylinder is embedded in the free space then the gain has directive pattern. It is also studied that if both layers are dielectric or magnetic types and embedded in a Mu Negative medium then its gain pattern becomes more directive with the maximum gain in the forward direction.

An axially slotted cylinder with specific inhomogeneous coatings

2017 ◽  
Vol 9 (10) ◽  
pp. 1915-1924
Author(s):  
Z.A. Awan
Keyword(s):  
Numerical Simulations ◽  
Forward Direction ◽  
Different Types ◽  
Inhomogeneous Coating ◽  
Coating Layers

An axially slotted cylinder coated with two different types of inhomogeneous coating layers is considered. These inhomogeneous coatings have decreasing permittivity profiles. The effects of various parameters of these coatings upon the gain pattern have been investigated using numerical simulations. It is studied that the gain at certain observation angles can be enhanced or diminished by controlling the inhomogeneity parameters of these considered profiles. It is further studied that for specific type of considered inhomogeneous coatings, the forward direction gain can be enhanced significantly.

scholarly journals Results of an intercomparison for free space antenna factor measurements within the German Calibration Service (DKD)

2016 ◽  
Vol 14 ◽  
pp. 11-16
Author(s):  
Thomas Kleine-Ostmann ◽  
Frank Huncke ◽  
Dieter Schwarzbeck ◽  
Otto Martetschläger ◽  
Jürgen Gaßner ◽  
...  
Keyword(s):  
Free Space ◽  
Frequency Range ◽  
Space Antenna ◽  
Different Types ◽  
Antenna Factor

Abstract. In this paper we discuss the results of an intercomparison for free space antenna factor measurements performed within the German Calibration Service (DKD). Three different types of antennas covering the frequency range from 30 MHz to 26.5 GHz have been calibrated in five different laboratories using different methods and calibration sites to obtain the free space antenna factor. The results agree well within the uncertainties specified by the laboratories suggesting that different approaches and different measurement sites to obtain the free space antenna factor are well compatible.

Performance Evaluation of SAC-OCDMA System in Free Space Optics and Optical Fiber System Based on Different Types of Codes

2017 ◽  
Vol 96 (2) ◽  
pp. 2843-2861 ◽  
Author(s):  
Salwa Mostafa ◽  
Abd El-Naser A. Mohamed ◽  
Fathi E. Abd El-Samie ◽  
Ahmed Nabih Zaki Rashed
Keyword(s):  
Performance Evaluation ◽  
Optical Fiber ◽  
Free Space ◽  
Free Space Optics ◽  
Fiber System ◽  
Space Optics ◽  
Different Types

scholarly journals Effect of Dissipative and Dispersive DNG Material Coating on the Scattering Behavior of Parallel Nihility Circular Cylinders

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Shakeel Ahmed ◽  
Muhammad Naveed ◽  
Abdul Ghaffar ◽  
Aqeel A. Syed ◽  
Q. A. Naqvi
Keyword(s):  
Plane Wave ◽  
Electromagnetic Scattering ◽  
Iterative Procedure ◽  
Coating Layer ◽  
Circular Cylinders ◽  
Double Negative ◽  
Double Positive ◽  
Different Types ◽  
Coating Layers ◽  
Expansion Coefficients

Electromagnetic scattering from coated nihility circular cylinders, illuminated byE-polarized plane wave, is investigated using an iterative procedure. Cylinders are infinite in length. The boundary conditions are applied on the surface of each cylinder in an iterative procedure in order to solve for the field expansion coefficients. The effect of different types of the coating layers including double positive (DPS) and double negative (DNG) on the alteration of the forward and backward scattering has been observed. Specially, the effect of dispersive and dissipative DNG coating layer has been focused. Numerical verifications are presented to prove the validity of this formulation by comparison with the published literature.

scholarly journals The Analysis of a Wideband Strip-Helical Antenna with 1.1 Turns

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Xihui Tang ◽  
Botao Feng ◽  
Yunliang Long
Keyword(s):  
Circular Polarization ◽  
Free Space ◽  
Relative Permittivity ◽  
Impedance Matching ◽  
Ground Plane ◽  
Coaxial Cable ◽  
Helical Antenna ◽  
Directional Radiation ◽  
Metallic Strip ◽  
Operation Frequency

A wideband strip-helical antenna with 1.1 turns is analyzed numerically and experimentally. By replacing the traditional wire helix with wide metallic strip, the forward traveling current on the strip helix with about one turn smoothly decays to the minimum value at the open end of the helix. Therefore, the strip helix can excite a wideband circular polarization (CP) wave with 50-ohm impedance matching. The proposed antenna is printed on a hollow-cylinder with a substrate relative permittivity ofεr=2.2and a thickness ofh=0.5 mm. A 50 Ω coaxial cable is directly connected to excite the strip-helical antenna without any additional impedance matching section. The ground plane is placed below the antenna in order to provide a directional radiation pattern. To demonstrate this method, a prototype of 1.1-turn strip-helical antenna is tested. The test shows that the proposed antenna can reach an overlapped bandwidth of 46% with height of 0.52λ0, whereλ0is the wavelength in free space at the center operation frequency.

scholarly journals Inside out Capping Clusters: Matryoshka Series

2018 ◽  
Vol 10 (4) ◽  
pp. 38
Author(s):  
Enos Masheija Rwantale Kiremire
Keyword(s):  
Transition Metals ◽  
Outer Layer ◽  
Series Method ◽  
Hypothetical Model ◽  
Different Types ◽  
New Type ◽  
First Time ◽  
Inside Out ◽  
Connectivity Rule ◽  
Cluster Series

Matryoshka clusters have been analyzed and categorized using skeletal numbers for the first time. They have been found to portray a unique way of capping by having the nuclear elements occupying the outer layer and what were supposed to be the capping elements on the outside taking the place of the nucleus. Hence they belong to a new type of cluster series. The different types of capping clusters have been identified. Isomeric graphical structures of the clusters can be constructed in accordance with the connectivity rule of the series. It appears that the elements with large skeletal numbers have a tendency of going inside and forming an icosahedral shape. The 4N series method is a useful hypothetical model for analyzing and categorizing clusters of the main group and transition metals.

scholarly journals Mie Scattering by a Conducting Sphere Coated Uniaxial Single-Negative Medium

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
You-Lin Geng
Keyword(s):  
Electromagnetic Scattering ◽  
Free Space ◽  
Three Dimensional ◽  
Mie Scattering ◽  
Wave Functions ◽  
Electrical Field ◽  
Vector Wave ◽  
Conducting Sphere ◽  
Negative Medium ◽  
Spherical Vector

We propose an accurate analytical method to compute the electromagnetic scattering from three-dimensional (3D) conducting sphere coated uniaxial anisotropic single-negative (SNG) medium. Based on the spherical vector wave functions (SVWFs) in uniaxial anisotropic medium, the electromagnetic field in homogeneous uniaxial SNG medium and free space can be expressed by the SVWFs in uniaxial SNG medium and free space. The continued boundary conditions of electromagnetic fields between the uniaxial SNG medium and free space are applied, and the tangential electrical field is vanished in the surface of conducting sphere, the coefficients of scattering fields in free space can be derived, and then the character of scattering of conducting sphere coated homogeneous uniaxial SNG medium can be obtained. Some numericals are given in the end.

scholarly journals Profiles of relative permittivity and electrical conductivity from unsaturated soil water content models

2016 ◽  
Vol 59 (3) ◽  
Author(s):  
Roberta Porretta ◽  
Fabio Bianchi
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Relative Permittivity ◽  
Chemical Properties ◽  
Geophysical Investigation ◽  
Empirical Relations ◽  
Different Types ◽  
Physical And Chemical

<p>A mathematical model of water diffusion in the vadose zone has been implemented for different types of soil textures in order to determine the soil water content (SWC) profiles in dependence of depth and time. From these profiles, obtained for different soils, we derived the characteristic electrical parameters, such as relative permittivity (<span class="gt-card-ttl-txt">epsilon</span><span><sub>r</sub></span>) and electrical conductivity (<span>sigma</span>), and their variation in time, employing empirical relations available in the scientific literature. The simulation through mathematical models has been performed taking into account different types of soils characterized by the percentage composition of sand, clay and silt in the textural triangle, which provides some physical and chemical properties that affect the water retention in the soil. The resulting simulated profiles of SWC and consequently permittivity and conductivity profiles, span over a certain range of values suggesting the best techniques and the limits in geophysical investigation. Moreover this a-prior knowledge helps in the elaboration and interpretation of permittivity and conductivity data obtained by the measurements. Permittivity and conductivity profiles are particularly useful in some environmental applications when the soil textures are (or supposed to be) known as in the typical case of landfill leachate dispersion. Since the soil textures beneath or nearby a disposal waste are characterized by a SWC, the values of (<span class="gt-card-ttl-txt">epsilon</span><sub>r</sub>) and (sigma) at various depth can be directly inferred.</p>

Fabrication of graphene-magnetite multi-granule nanocluster composites for microwave absorption application

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4097-4103
Author(s):  
Boo H An ◽  
Bum C Park ◽  
Hamad A Yassi ◽  
Ji S Lee ◽  
Jung-Rae Park ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Microwave Absorption ◽  
Free Space ◽  
Relative Permittivity ◽  
Horn Antennas ◽  
Microwave Absorbing Properties ◽  
X Band ◽  
Permittivity And Permeability ◽  
Free Space Method ◽  
Space Method

Ferrite multi-granule nanoclusters are fabricated for microwave absorption materials in different sized particles and granules by modified polyol process. Various sizes of ferrite nanoclusters are placed on graphene-based composites and the behavior of their microwave absorbing properties is studied. The absorbing properties are measured using the free-space method with two horn antennas for X-band range (8.2 GHz–12.4 GHz). Relative permittivity and permeability values are calculated in measured frequency domain. The absorption coefficient changes by forming ferrite-graphene composites are presented as well.

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