摘要:

AbstractThis paper shows that the surface current density can be calculated by using approximate total tangent magnetic vector fields which are expressed by finite number of linear combination of tangent vectors of spherical wave functions. Sampling points are determined by considering the property of associated Legendre functions and trigonometrical functions. By setting a number of sampling points to twice the largest mode number, a computer‐aided algorithm is obtained. the accuracy of the solutions is checked and the polarization dependence of the surface current densities is clarifie

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe performance of the 35‐GHz nonradiative dielectric waveguide (NRD‐guide) transmitter and receiver has been improved and they have been reduced in size. the miniaturization of the transmitter has been proposed by reducing the size of the terminator. Since the reflection of the balanced mixer for heterodyne detection has been reduced, miniaturization of the receiver is obtained by removing the circulator used for protection from reflection. the new transmitter and receiver are reduced to half their earlier sizes. Their frequency stability is less than −0.6 ppm/°C. Moreover, horn antennas with rigidity and air tightness are connected to the transmitter and re

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe fundamental characteristics of the coupling efficiency between two anisotropic slab waveguides with different configurations butt‐joined via a gap are analyzed in the case of a TM mode incidence by means of a single‐mode slab waveguide model made of equatorial dielectric tensor. the electromagnetic field in the gap is represented by a combination of the forward elementary plane wave propagating from the incident side to the output waveguide and the backward elementary plane wave propagating in the opposite direction.By applying the boundary conditions, the power transmission and reflection coefficients in the guided‐wave system are computed. Further, the effects of the lateral misalignment and inclination between the wave‐guides and the index of refraction and spacing of the gap on the coupling efficiency are studied based on the numerical results. an optimum condition to maximize the coupling efficiency is o

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe GaInAsP/InP circular planar‐buried heterostructure is a promising structure to realize a low‐threshold 1.3‐μm surface‐emitting laser for continuous operation at room temperature. In the conventional regrowth process, pinholes which depend on the crystalline orientation of the circular active region tend to occur, resulting in the increase of nonradiative current. As a result, it has been difficult to achieve room temperature oscillation.To solve this problem, the planar‐buried structure which could be formed by one liquid‐phase epitaxial step without using a mask was adopted to fabricate mesa‐type surface‐emitting lasers. As a result, the reproducibility in forming the buried structure was improved and the non‐radiative current decreased. the resultant devices showed stable electrical and optical characteristics.When the laser cavity was formed by using SiO2/Si dielectric multilayer mirrors, continuous oscillation was observed at 77 K and the threshold currents of 15 devices were lower than 15 mA. the lowest threshold current was 2.2 mA.In the room‐temperature pulse operation, the threshold current was 34 mA, the lowest among the values ever reported. Pulse oscillation was observed at 45°C and continuous operation was observed even at −57°C.If reflecting mirrors with a high thermal conductivity are introduced, the temperature for continuous operation will increase and it will be possible to realize continuous opera

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractIn principle, the finite element method is an analysis method in which an inhomogeneous waveguide with a closed boundary and a complex geometry. By contrast, the boundary element method is suited for the analysis of an open‐region problem.In this paper, as a method for analyzing the propagation characteristics of the guided modes in an open waveguide, the finite element method is applied to the electromagnetic field of the interior region while the boundary element method is applied to the field outside the waveguide. the fields of the two regions are then connected at the boundary.By means of the present method, it is possible to analyze without spurious solutions the guided modes in an open waveguide with a cladding made of a different material and an inhomogeneous interior region with a complex geometry. Also, the coefficient matrix of the matrix equation to be solved becomes square. As practical examples, the dispersion characteristics of the rectangular dielectric waveguides and channel waveguides are analyzed so that the validity of the method is verifie

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractTo carry out numerical calculations efficiently based on the discrete Fourier transform (DFT), the filtering operator with regard to the discrete spectrum is defined and its applications are described. First, for the simultaneous equations containing discrete convolution operations similar to the Wiener‐Hopf‐type integral equation of the first kind, a study is made to determine if a solution method similar to the Wiener‐Hopf technique in the continuous spectrum can be applied. Since the DFT is based on the periodic functions, it is found that such a method is not possible in general except for special cases.To derive numerical solutions, three methods are proposed in this paper. In the first method, the simultaneous equations derived by using the inner product on the discrete spectrum are solved directly. the next method is a successive solution by repetition of the filtering operation. the last method is a successive solution by repetition of the filtering operation. the last method uses a conjugate gradient method based on the filtering operation. As an example of application of the numerical method based on the conjugate gradient method which can be applied to a wide range of problems, the problem of scattering of electromagnetic waves by a planar grating is investigated. It is shown that the transmitted power and the surface current distribution can be obtained accur

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe MIS field effect has been confirmed in superconductors by effectively using a low carrier density in oxide high‐temperature superconductors. Based on this principle, a superconductor field effect transistor has been created. the experimental device uses an MIS diode and MISFET with Au/(100)SrTiO3/(001)YBaCuO structure grown by selective heteroepitaxy. the drain current could be decreased and increased by positive and negative gate fields. When cooled below the critical temperature, both the superconducting critical current and the flux‐flow resistance were modulated by the gate field. By approximating the high temperature superconductor with a degenerate semiconductor band model and introducing the Bardeen‐Stephen magnetic flux resistance and the flux‐creep concept, the operation mechanism of the superconductor MISFET can be ex

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractAn ultrahigh‐speed 32 K ×8/×9 TTL bi‐CMOS SRAM with a 5‐ns standard access time was developed using a five‐layer polysilicon/two‐layer aluminum 0.6‐μm bi‐CMOS process with 4.2 × 5.6‐μm24‐M SRAM‐class small‐size memory cells, ultrahigh capacity, self‐aligned bipolar electrodes with 18.5‐GHz cutoff frequency and 0.6‐μm/0.7‐μm (nMOS/pMOS) gate‐length MOS transistors. This fast access time was achieved by using center power pin‐out to reduce output noise, a major problem in the TTL SRAM, together with alternated bit line load architecture, a memory array architecture well suited to center power pin‐out. Also used were a bit‐line load circuit for rapid precharging of the bit line and

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractUsing PLZT, which is a transparent ceramic with an electrooptical property, an electrooptical device for high‐speed modulation was fabricated. PLZT was synthesized by the oxide mixing method and the oxalate method in ethanol solution.Using ethanol as a dispersion medium in the former method, the grain size which strongly influences the transmittance can be controlled. the structure of the optical shutter made of PLZT was determined by investigating the electric field distribution in the unit device forming the shutter by the finite element method. Then the optical shutter was formed by patterning the PLZT wafer using photolithography.A three‐dimensional (3‐D) image display system by stereoscope was constructed. the PLZT device was capable of switching display image at 60 and 120 Hz. This device was also usable for 3‐D image

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractContact components have been used widely for switches, relays, and connectors. Although they have a simple structure, they are very reliable, having low resistance at on‐time and high resistance at off‐time, and are relatively immune against external noise. As a result, there has been a constant increase in demand for such components. However, because the contact surface may get contaminated, oxidized, or damaged over a long period of time or just through many cycles of usage, they may fail in conduction. Thus, very little information is available as to the relation between the surface state and the conductive phenomenon.The electric conductivity has been studied in conjunction with the surface state using a finite element method. A current density distribution inside a contact spot was calculated. As a result, when the resistivity of the contact spot is small, the current was found not to distribute uniformly throughout the spot area but increases at the corners of the spot when the spot shape is square. This means that the electric conductivity is proportional to the circumference length of the spot. On the other hand, as the resistivity of the spot increases, the current density at corners and circumferential regions decreases gradually and finally becomes uniform in its distribution over the entire spot region. In this case, the electric conductivity is shown schematically and quantitatively to be proportional to the a

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY