Paraxial space-domain formulation for surface fields on a large dielectric coated circular cylinder

A new method to evaluate the surface fields excited within the paraxial (nearly axial) region of an electrically large dielectric coated circular cylinder is presented. This representation is obtained by performing the Watson's transformation in the standard eigenfunction solution and using the fact that the circumferentially propagating series representation of the appropriate Green's function is periodic in one of its two variables. Therefore, it can be approximated by a Fourier series where the two leading terms of the expansion yield engineering accuracy in most cases. This work can be used in conjunction with a method of moments solution for the design/analysis of conformal microstrip antennas and arrays. Numerical results are presented and compared with a standard eigenfunction expansion.     

Electromagnetic reflection from a curved dielectric interface

The reflection of a high-frequency electromagnetic field from an arbitrarily curved dielectric interface is considered. The fields are expanded in asymptotic series ofk^{-1}, known as Luneburg-Kline expansions. Based on a ray method the zero- and first-order terms ofk^{-1}of the reflected and transmitted field are evaluated at the interface. Associated with the fields at the interface, effective surface current densities can be used to determine the reflected and transmitted field at points away from the interface, which is done analytically for the reflected far field in the case of plane wave incidence. The result consists of a frequency-independent term, which is related to geometrical optics solution, and a term ofk^{-1}, which is a useful extension of geometrical optics solution in some cases.     

Time-domain analytic and numeric analysis of vertical dipoles infront of a dielectric planar interface

Potentials excited by impulsive vertical electric and magnetic dipoles in a geometry of two dielectric media with a planar interface are studied both analytically and numerically. Closed-form expressions for the Hertzian potential are derived in cases when the observation point is on the axis of the dipole or when both the dipole and the observation point are located at the interface. Numerical results are given for more general observation points     

Lateral interface effect on pulsed DC electromigration analysis

DC and Pulsed DC Electromigration tests at 1Hz and lOkHz have been performed on two single level Al-0.5%Cu metallizations. The Black's parameters have been analysed with a great confidence level using a statistical global approach. The results are in agreement with the Average Current Model at 10kHz and with the On-Time Model at 1Hz considering that thermal effects not only affect the current density exponent n, but also the duty cycle accelerating factor m. The extracted activation energies reflect the same diffusion mechanisms for the two metallizations. Microscopic observations showed huge metal accumulations for each structure and emphasized the influence of the resist stripping stage on the electromigration behaviour of the samples.     

Field near the interface of a jungle dielectric slab

The transmitted far field of a short vertical dipole located in a jungle dielectric medium is evaluated by the steepest-descent technique. At near-grazing angles of transmission, the technique is modified to account for the influence of the branch point. The influence is found significant only in the field amplitude and is confined within a short distance from the jungle-air interface, within which the difference between the path of the geometric-optical wave and that of the lateral wave is less than a wavelength.     

Comments on `Refraction at a curved dielectric interface:geometrical optics solution'

For the original article see ibid., vol.30, no.1, p.12-19, 1982. An error in the solution by S.W. Lee et al. of the problem of transmission of a spherical or plane wave through an arbitrary curved dielectric interface is discussed     

Capacitance-voltage analysis of a high-k dielectric on silicon

正Device characteristics of TiO_2 gate dielectrics deposited by a sol-gel method and DC sputtering method on a P-type silicon wafer are reported.Metal-oxide-semiconductor capacitors with Al as the top electrode were fabricated to study the electrical properties of TiO_2 films.The films were physically characterized by using X-ray diffraction,a capacitor voltage measurement,scanning electron microscopy,and by spectroscopy ellipsometry.The XRD and DST-TG indicate the presence of an anatase TiO_2 phase in the film.Films deposited at higher temperatures showed better crystallinity.The dielectric constant calculated using the capacitance voltage measurement was found to be 18 and 73 for sputtering and sol-gel samples respectively.The refractive indices of the films were found to be 2.16 for sputtering and 2.42 for sol-gel samples.     

An impedance sheet approximation for thin dielectric shells

An approximate equivalence between an impedance loaded surface and a thin dielectric shell is given. This approximation is used to compute the backscattering from a thin circular dielectric tube and the results are compared to the exact solution. Computations for backscattering from a thin dielectric cone-sphere and resonant wire loop inside of a thin dielectric cylinder are also given as further illustrations of the method.     

High frequency fields in the presence of a curved dielectric interface

A high-frequency line source in a dielectric medium that is separated by a concave cylindrical boundary from an exterior medium with lower dielectric constant generates a variety of wave phenomena which have been explored extensively. This problem is reexamined here with a view toward clarifying relevant reflection and transmission characteristics within the framework of ray optics, with emphasis on the more complicated transmitted field. The exterior domain is divided into illuminated and shadow regions separated by the transmitted tangent ray launched by a ray incident at the critical angle. Conventional ray optics is valid far from the tangent ray shadow boundary on the illuminated side. The shadow boundary is surrounded by transition regions wherein Fock type integrals and Weber functions yielding local lateral waves provide alternative representations. On the shadow side, not too far from the shadow boundary, the field can be interpreted via "tunneling" and subsequent radiation along a ray from a virtual caustic to the observer. The tunneling is associated with the initial evanescent decay of the transmitted field excited by a totally reflected incident ray. However, deeper inside the shadow, this mechanism is inapplicable, and the field is expressed either in terms of the Fock integrals or a creeping wave-type residue series. The results are presented in a format that permits insertion into a geometrical theory of diffraction (GTD) user's manual.     

An analysis technique for buried inhomogeneous dielectric objectsin the presence of an air-Earth interface

Complex geological structures are modelled in the presence of an air-Earth interface. A cross-borehole configuration of target, source, and receiver is assumed, with the target itself not restricted as to geometrical cross section or complex permittivity value. Two-dimensional method-of-moment formulations are employed, utilizing cylindrical pulse basis functions and point matching. Scattering from buried dielectric objects is computed near the air-Earth interface for both TE and TM incident fields. A Sommerfeld-Green function is used to represent the effect of the air-Earth interface on the incident fields and the impedance matrix. The TE case is examined for scattering of both the copolarized and cross-polarized electric fields, and several examples are given for a cylindrical target at depths that vary from one to twenty four wavelengths, after which the presence of the air-Earth interface can be neglected. Some experimental results utilizing a 1/40th laboratory scale model and a tunnel-like target are also included for comparison. The technique enables the user to investigate electromagnetic scattering from a variety of complex buried objects whose dimensions are typically in or below the resonance region. The simultaneous relaxation of restrictions on cross section, material properties, and burial depth, together with experimental validation, is not found in the literature to date     

Microwave-induced auditory effect in a dielectric sphere

The acoustic pressure wave generation inside an electromagnetically lossy dielectric sphere from an incident microwave pulse is analyzed rigorously. The pressure wave equation derived using the first-order approximation of a thorough formulation on microwave-induced thermoacoustic effect in dielectrics, is used. The inhomogeneous hyperbolic-type pressure wave differential equation is solved by a Green's function theory approach. The boundary conditions on the dielectric sphere-air interface are taken into account. The power is computed by applying the exact Mie theory solution for the dielectric sphere. Two types of acoustic waves are derived inside the sphere: (a) a transient burst type pressure wave, corresponding to the free-space contribution of Green's function; and (b) an infinite set of damped oscillations related to the normal acoustic modes of the spherical resonator. Numerical results are computed and presented for several cases     

Pulsed beam reflection and transmission at a dielectric interface:two-dimensional fields

Highly focused pulsed fields in vacuum can be generated analytically by assigning complex values to the space-time source coordinates of the conventional transient free-space Green's function. These new wave objects have been named complex-source pulsed beams (CSPB). Their utility can be extended to generating new solutions for pulsed beam propagation and diffraction in a perturbed environment by making the space-time source coordinates in the corresponding Green's function complex. The analytic extension required in this process is performed systematically via the spectral theory of transients. A canonical test case for reflection, including critical angle, lateral (head) wave and evanescent transmission effects, is provided by a dielectric half-space. The exact solution for CSPB scattering is derived in spectral integral form, evaluated in terms of the time-dependent spatial spectrum singularities in the complex plane, and interpreted physically. Numerical evaluation reveals the detailed space-time behavior of these physical constituents and their role in establishing the total scattered field. To simplify the analysis, a two-dimensional problem is considered wherein the pulsed beam is generated by a complex pulsed line source     

Impedance-type boundary conditions for a periodic interface betweena dielectric and a highly conducting medium

Using the homogenization method, we derive a generalized impedance-type equivalent boundary condition for the electromagnetic (EM) field at a two-dimensional (2-D) periodic highly conducting rough surface with small-scale roughness. The results obtained in this paper generalize ones obtained preciously for the case of a perfectly conducting rough surface. We will show that the coefficients in this equivalent boundary condition can be interpreted in terms of electric and magnetic polarizability densities. We also show that when the roughness dimensions are small compared to a skin depth of the conducting region (a smooth interface), the generalized impedance boundary condition given here reduces to the standard Leontovich (1948, 1985) condition. Results for the reflection coefficient of a plane wave incident onto a 2-D conducting interface are presented. We show the importance of the boundary-layer fields (as used in this study) over that of classical methods when calculating the reflection coefficient from a highly conducting rough interface. This work will lead to an analysis of the effects of surface roughness on power loss in MIMIC circuits     

On assumed boundary conditions at an interface between a dielectric and a compressible plasma

Some remarks are made concerning two assumed boundary conditions at the interface between a dielectric region and a compressible plasma. It is indicated that Fedorchenko's double Laplace integral formulation, which invokes causality, is equivalent to the assumption of continuity of the normal electric field. In general, this differs from results derived on the basis of an assumed rigid boundary. It is shown that both expressions for the reflection coefficient in the dielectric region have the same form, but the temperature correction is different. Without appeal to the physics of the sheath, there is no reason to choose one condition over the other.     

Two-dimensional analysis of a dielectric waveguide mirror

We present the two-dimensional (2-D) mode numerical analysis of a dielectric waveguide mirror with arbitrary structure angle. This work is an extension of a previously reported one-dimensional (1-D) mode analysis which accounts for the transverse variation, in addition to the lateral, of the waveguide modes. Inclusion of the transverse confinement is very important and has a significant effect on the predicted characteristics of the dielectric mirror. The dependence of the modal reflection on mode confinement and transverse and lateral mirror tilt is evaluated. In addition, the farfield is predicted and results in an unusual and unique crescent shaped distribution for angled incidence to the mirror. These mirrors are finding increasing use in many optical devices and systems including turning mirrors, lasers, and optical switches and couplers. With this expanding application, the characterization of these mirrors is paramount     

Electrodynamic analysis of irregularities based on a shielded dielectric waveguide

Several functional elements exhibiting filtering properties are calculated on the basis of a rigorous solution to the 3D problem of diffraction by a junction of shielded dielectric waveguides (SDWs). It is shown that the solution to the diffraction problem depends heavily on the SDW dispersion characteristics that contain two-value sections in the region of propagating waves and indicate the presence of backward waves in regular waveguides. It is demonstrated that parallelepiped dielectric waveguides placed in the interior of a shielded waveguide enhance the efficiency of small bandpass filters.     

Capacitance-voltage analysis of a high-k dielectric on silicon

Device characteristics of TiO₂ gate dielectrics deposited by a sol-gel method and DC sputtering method on a P-type silicon wafer are reported. Metal-oxide-semiconductor capacitors with Al as the top electrode were fabricated to study the electrical properties of TiO₂ films. The films were physically characterized by using X-ray diffraction, a capacitor voltage measurement, scanning electron microscopy, and by spectroscopy ellipsometry. The XRD and DST-TG indicate the presence of an anatase TiO₂ phase in the film. Films deposited at higher temperatures showed better crystallinity. The dielectric constant calculated using the capacitance voltage measurement was found to be 18 and 73 for sputtering and sol-gel samples respectively. The refractive indices of the films were found to be 2.16 for sputtering and 2.42 for sol-gel samples.     

Brewster angle effect on the performance of omni-directional circular dielectric grating antenna-improved perturbation analysis

The radiation characteristics of the omni-directional periodic leaky wave antenna operating in TMol mode is investigated by the improved perturbation method with a particular attention directed to the Brewster angle effect on the performance of the antenna, and some interesting results are given.     

傍轴光束薄透镜传输的统计行为

在光流体模型(HMO)的理论基础上,引用等效高斯光束方法,研究了傍轴光束的薄透镜传输的统计行为,给出了像差的处理方法并讨论了像差对光束质量因子的影响。     

Generation of complex Gaussian beam modes in beam interaction with a planar dielectric interface

The problem of Gaussian beam interaction with a planar interface separating two semi-infinite homogeneous isotropic lossless media is considered for regular incidence, i.e., excluding the case of total internal reflection. The reflected and refracted fields are expressed in terms of the fundamental and higher order complex beam modes. These newly identified complex beam modes differ from the conventional beam modes and they describe the structure of the reflected and transmitted fields in a more convenient manner.