scholarly journals Scattering from a Buried PEMC Cylinder Illuminated by a Normally Incident Plane Wave Propagating in Free Space

2018 ◽  
Vol 8 (1) ◽  
pp. 1-7 ◽  
Author(s):  
A. Hamid ◽  
F. Cooray
Keyword(s):  
Plane Wave ◽  
Half Space ◽  
Free Space ◽  
Transverse Magnetic ◽  
Planar Interface ◽  
Burial Depth ◽  
Multiple Reflections ◽  
Incident Plane ◽  
Plane Wave Incident ◽  
Expansion Coefficients

A rigorous solution is presented to the problem of scattering by a perfect electromagnetic conducting (PEMC) circular cylinder buried inside a dielectric half-space that is excited by a normally incident transverse magnetic (TM) plane wave propagating in free space. The plane wave incident on the planar interface separating the two media creates fields transmitting into the dielectric half- space becoming the known primary incident fields for the buried cylinder. When the fields scattered by the cylinder, in response to those fields incident on it, are incident at the interface, they generate fields reflected into the dielectric half-space and fields transmitted into free space. These fields, and the fields scattered by the cylinder are expressed in terms of appropriate cylindrical waves consisting of unknown expansion coefficients which are to be determined. Imposing boundary conditions at the surface of the cylinder and at a point on the planar interface, enables the evaluation of the unknown coefficients. This procedure is then replicated, by considering multiple reflections and transmissions at the planar interface, and multiple scattering by the cylinder, till a preset accuracy is obtained for the reflection coefficient at the particular point on the interface. The refection coefficient at this point is then computed for cylinders of different sizes, to show how it varies with the PEMC admittance of the cylinder, its burial depth, and the permittivity of the dielectric half-space.

REPLY BY D. RANKIN TO THE DISCUSSION BY J. T. WEAVER

Geophysics ◽  
1963 ◽  
Vol 28 (3) ◽  
pp. 490-490
Author(s):  
D. Rankin
Keyword(s):  
Electromagnetic Field ◽  
Plane Wave ◽  
Radiation Field ◽  
Free Space ◽  
Wave Incident ◽  
Induction Field ◽  
The Earth ◽  
Plane Wave Incident

I am indebted to Weaver if he has indeed clarified certain points which I had previously considered to be obvious. Cagniard (1953) states explicitly the magnitude of the wavelengths in free space and it is further implicit in the work of Rankin (1962) that it is indeed this same electromagnetic field which is being considered. The plane wave aspect of the problem arises from the extent of and not the distance from the source so that truly it is the induction field and not the radiation field that is under discussion. I had believed, until this note by Weaver, that d’Erceville and Kunetz (1962) also considered a plane wave incident on the earth and in fact that I was merely following both Cagniard and d’Erceville and Kunetz in this matter. The consistency of the results would tend to confirm this belief.

Hybrid‐ray approximation in electromagnetic sounding

Geophysics ◽  
1979 ◽  
Vol 44 (11) ◽  
pp. 1846-1861 ◽  
Author(s):  
Tze‐Kong Kan ◽  
C. S. Clay
Keyword(s):  
Half Space ◽  
Wave Theory ◽  
Transverse Magnetic ◽  
Image Method ◽  
Multiple Reflections ◽  
Current Dipole ◽  
Electromagnetic Sounding ◽  
Transmission Coefficients ◽  
Magnetic Components ◽  
A Current

Our purpose is to develop electromagnetic (EM) transient sounding methods that can handle resistivity structures having dipping interfaces. The method is an approximation that uses wave theory for part of the calculation and ray theory for the rest. The approximation is a refinement of Yost’s (1952) image method in which the source on a half‐space becomes the image beneath the reflecting interface. This approach shows excellent agreement with experiment and promises simple applications. To test the approximation, we compare numerical integration of the fields over a two‐layer half‐space with approximate values. We separate the EM integrals into integrals for the surface wave, primary, and multiple reflections. For a current dipole along the x‐axis, the electric field [Formula: see text] is the sum of the transverse electric and transverse magnetic components. For skin depths >1, the main contributions to the integrals come from directions near the specular direction, and by moving the reflection coefficients at the lower interface outside of the integral, we obtain the hybrid‐ray approximation. The transmission coefficients from the source into the earth remain inside because the source is near the interface. Computations for a two‐layer model that includes the geometry, and system functions for deep dipole‐dipole soundings in the Precambrian shield of northern Wisconsin, give time‐domain signals that closely approximate the measurements. The theoretical model consists of a layer 18 to 23 km thick with a conductivity of [Formula: see text] over a half‐space with a conductivity of [Formula: see text].

scholarly journals Scattering from a Buried PEMC Cylinder due to a Line Source Excitation above a Planar Interface Between Two Isorefractive Half Spaces

2019 ◽  
Vol 8 (4) ◽  
pp. 1-6 ◽  
Author(s):  
A. K. Hamid ◽  
F. Cooray
Keyword(s):  
Circular Cylinder ◽  
Boundary Conditions ◽  
Half Space ◽  
Line Source ◽  
Planar Interface ◽  
The Other ◽  
Burial Depth ◽  
Cylinder Axis ◽  
Electric Line ◽  
Source Excitation

A solution to the problem of scattering from a perfect electromagnetic conducting (PEMC) circular cylinder   buried inside a half-space and excited by an infinite electric line source is provided. The line source is parallel to the cylinder axis, and is located in the other half-space. The two half spaces are isorefractive to each other. The source fields when incident at the planar interface separating the two half spaces, generate fields that are transmitted into the half-space where the cylinder is. These fields then become the known basic incident fields for the buried PEMC cylinder. Scattering of these incidents fields by the cylinder will consequently generate fields at the interface that get reflected back into the same half-space and transmitted frontward into the source half-space, all of which are unknown. Imposing appropriate boundary conditions at the surface of the buried cylinder and at a specified point on the interface, enables the evaluation of these unknown fields. The refection coefficient at the specified point is then computed for cylinders of different sizes, to demonstrate how it varies with the PEMC admittance of the buried cylinder, the intrinsic impedance ratio of the two isorefractive half-spaces, and the burial depth of the cylinder.

Microwave Non-Destructive Testing of Coatings and Paints Using Free Space Microwave Measurement

2005 ◽  
Vol 2 (2) ◽  
pp. 17
Author(s):  
Norhayati Hamzah ◽  
Deepak Kumar Ghodgaonkar ◽  
Kamal Faizin Che Kasim ◽  
Zaiki Awang
Keyword(s):  
Free Space ◽  
Protective Coatings ◽  
Microwave Measurement ◽  
Multiple Reflections ◽  
Destructive Testing ◽  
Lens Antennas ◽  
Coatings And Paints ◽  
Microwave Nondestructive Testing ◽  
Mode Transitions ◽  
Diffraction Effects

Microwave nondestructive testing (MNDT) techniques are applied to evaluate quality of anti-corrosive protective coatings and paints on metal surfaces. A tree-space microwave measurement (FSMM) system is used for MNDT of protective coatings. The FSMM system consists of transmit and receive spot-focusing horn lens antennas, a vector network analyzer, mode transitions and a computer. Diffraction effects at the edges of the sample are minimized by using spot-focusing horn lens antennas. Errors due to multiple reflections between antennas are corrected by using free-space LRL (line, reflect, line) calibration technique. We have measured complex reflection coefficient of polyurethane based paint which is coated on brass plates.

scholarly journals Core-Shell Nano-Antenna Configurations for Array Formation with More Stability Having Conventional and Non-Conventional Directivity and Propagation Behavior

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 99
Author(s):  
Qaisar Hayat ◽  
Junping Geng ◽  
Xianling Liang ◽  
Ronghong Jin ◽  
Sami Ur Rehman ◽  
...  
Keyword(s):  
Plane Wave ◽  
Propagation Direction ◽  
Core Shell ◽  
Incident Plane Wave ◽  
Polarization Direction ◽  
Shell Nanoparticles ◽  
Incident Plane ◽  
Core Shell Nanoparticles ◽  
Coated Nanoparticle ◽  
2D Array

The enhancement of optical characteristics at optical frequencies deviates with the choice of the arrangement of core-shell nanoparticles and their environment. Likewise, the arrangements of core-shell nanoparticles in the air over a substrate or in liquid solution makes them unstable in the atmosphere. This article suggests designing a configuration of an active spherical coated nanoparticle antenna and its extended array in the presence of a passive dielectric, which is proposed to be extendable to construct larger arrays. The issue of instability in the core-shell nanoantenna array models is solved here by inserting the passive dielectric. In addition to this, the inclusion of a dielectric in the array model reports a different directivity behaviour than the conventional array models. We found at first that the combination model of the active coated nanoparticle and passive sphere at the resonant frequency can excite a stronger field with a rotated polarization direction and a propagation direction different from the incident plane-wave. Furthermore, the extended 2D array also rotates the polarization direction and propagation direction for the vertical incident plane-wave. The radiation beam operates strong multipoles in the 2D array plane at resonant frequency (behaving non-conventionally). Nevertheless, it forms a clear main beam in the incident direction when it deviates from the resonance frequency (behaving conventionally). The proposed array model may have possible applications in nano-amplifiers, nano-sensors and other integrated optics.

A STUDY OF TWO‐DIMENSIONAL HEAD WAVES IN FLUID AND SOLID SYSTEMS

Geophysics ◽  
1963 ◽  
Vol 28 (4) ◽  
pp. 563-581 ◽  
Author(s):  
John W. Dunkin
Keyword(s):  
Half Space ◽  
Vertical Displacement ◽  
Point Of View ◽  
Head Wave ◽  
Apparent Velocity ◽  
Two Dimensional ◽  
Multiple Reflections ◽  
Transient Wave ◽  
Line Load ◽  
Head Waves

The problem of transient wave propagation in a three‐layered, fluid or solid half‐plane is investigated with the point of view of determining the effect of refracting bed thickness on the character of the two‐dimensional head wave. The “ray‐theory” technique is used to obtain exact expressions for the vertical displacement at the surface caused by an impulsive line load. The impulsive solutions are convolved with a time function having the shape of one cycle of a sinusoid. The multiple reflections in the refracting bed are found to affect the head wave significantly. For thin refracting beds in the fluid half‐space the character of the head wave can be completely altered by the strong multiple reflections. In the solid half‐space the weaker multiple reflections affect both the rate of decay of the amplitude of the head wave with distance and the apparent velocity of the head wave by changing its shape. A comparison is made of the results for the solid half‐space with previously published results of model experiments.

Sign in / Sign up

Export Citation Format

Share Document