摘要:

AbstractRecently, computer aided design (CAD) for microwave or millimeter‐wave devices has become very important. In particular, the necessity of simulation of a system based on numerical analysis has increased. Analysis on the time domain is available for estimating pulse propagation characteristics on high‐speed devices.For this purpose, this paper proposes the spatial network method using full electromagnetic components and presents its characteristics.However, the time‐step in iterative computation is the same in the whole system and it demands the same space difference length corresponding to the same wave propagation time.The forementioned limitation becomes an obstacle for an efficient analysis of a large model with high accuracy, since many discretized points increase memory and computing time.Finally, a variable difference method of space in the spatial network method is described by using delay characteristics of lumped circuit elements at each

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730801

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

年代:1990

数据来源: WILEY

摘要:

AbstractRecently, a significant effort has been spent on research related to radiating X‐rays, and new X‐ray optical devices have been developed. However, in this case, the problem has arisen of scattering of the incident light or the X‐ray by atoms in the medium. When an X‐ray or a short wavelength optical beam is incident on a fiber, the incident light is scattered by the atoms and a part of the scattered light is radiated so that the energy ratio captured in the fiber is decreased. To minimize this effect, it is necessary to optimize the shape and the refractive index of the fiber.In this paper, the theory of radiation from an electric dipole which has been used in atmospheric communication is used for the first time to study the problem of scattering by the atoms. By the application of this theory, the scattering problem can be solved easily.The energy fraction captured in the fiber for the normalized fiber thickness, which has been obtained only for each mode, is now computed adding the higher‐order modes. The results are compared with those in the absence of scattering. It is found that, although the power can be trapped well inside the fiber by increasing the normalized fiber thickness in the case without scattering, the loss cannot be eliminated if scatteri

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730802

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

年代:1990

数据来源: WILEY

摘要:

AbstractAn effective numerical method is presented for the induced current distribution on a conductor surface when electromagnetic waves with general complex amplitude such as Gaussian beam waves are incident on a perfectly conducting circular cylinder. Up to the radius of the wavelength, the surface current can be analyzed accurately by the boundary element method. For a further increased radius, the execution time for calculation is increased or the memory storage capacity becomes insufficient. The direct method by obtaining inverse matrices becomes computationally difficult.It had not been known that the coefficient matrix is a cyclic matrix for the resulting matrix equation when the integral equations of the surface current are made discrete. This matrix equation can be solved effectively through a discrete Fourier transform without obtaining the inverse matrix. Examples of numerical calculations are shown in which the method presented here was applicable for a radius which ranged from a wavelength to several tens of wavelength.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730803

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of polarization coupling which occurs in the coupler comprising the ring resonator for a fiber‐optic ring‐resonator gyro was studied. First, it is confirmed theoretically and experimentally that the resonant waveform in the ring resonator changes significantly by the polarization coupling. It is shown that the incline angle between the principal axes of two optical fibers causing the polarization coupling can be measured indirectly by observation of the resonant waveform.Next, three factors causing the drift are identified in the case of a fiber‐optic gyro using a ring resonator with polarization coupling. The magnitude of the drift for each factor is found quantitatively. As a result, it is found that the drift of about 10−7‐ 10−5rad/s is generated in a typical case. Methods for reducing these drifts are presented. Finally, a rotation sensitivity of 1 × 10−5rad/s with a time constant of 10 s is obtained in an improved fi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730804

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

年代:1990

数据来源: WILEY

摘要:

AbstractA liquid crystal lens has a unique feature in that its focal length can continuously be varied between the values for the ordinary ray and the extraordinary ray by varying the applied voltage. However, the focal length begins to increase at the threshold voltage and saturates gradually as the applied voltage increases.In this paper, attempts are made to compensate or linearize the nonlinear properties of the liquid crystal lens. That is, transmission properties of a guest‐host cell or properties of the capacitance of a homogeneously aligned liquid crystal cell are used. Then the compensation is made by using their inverse functional signals as a driving voltage since these liquid crystal cells have properties similar to those of the liquid crystal lens.The driving voltage for the compensation can be produced by using a simple system with the liquid crystal cell in an electric circuit. Then the nonlinear properties of the lens can be improved. The temperature dependence of the compensation properties of this system and that of the liquid crystal lens show that the compensation is also effective for the temperature dependence. This is because the output voltage from the driving circuit varies to compensate the temperature dependence of the liquid crystal len

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730805

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper discusses rigorously the problem of scattering of an infinitely long strip conductor with an infinitesimal thickness illuminated by a plane electromagnetic wave with an arbitrary incident angle and an arbitrary polarization angle. The spectral domain method is used for the analysis. Numerical calculations are carried out for the scattered far field and the current distributions by discretization based on the sampling theorem.To reduce the computation time required for numerical integrations, the Weber‐Schafheitlin integral formula is introduced to the principal terms and the convergence is improved. According to the numerical results, accurate results are obtained for the far field and the current distributions for the strip width as wide as 10 wavelength

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730806

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe two‐dimensional scattering problem of electromagnetic wave by an inclined parallel strip grating with a periodic structure is analyzed by means of the formulation using the mutual field. A formulation is presented for the analysis of multiple scattering by a strip system with a periodic structure by means of the representation of the scattered field by one strip. The Wiener‐Hopf equations to be satisfied by each scattered field and the representation of scattered waves based on the solution to these equations are obtained. Since the width of the strip in the grating is finite, it is difficult to carry out rigorously the decomposition in the solution of the Wiener‐Hopf equations.The sampling theorem is used for expansion of the unknown function corresponding to the surface current on the strip into a series so that the Wiener‐Hopf equations are reduced to a set of simultaneous equations. In this procedure, the numerical analysis can be carried out independently of the Wood anomaly frequencies and the resonant frequencies between the strips.For evaluation of convergence and errors in the results, the relative error with respect to the extrapolated value and the square error for satisfaction of the boundary condition are computed numerically. The numerical results for the power transmission coefficient by the present method are compared with those by other

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730807

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe phase velocity of a T‐rod‐type dielectric loaded helix is determined by the developed helix method. Further, the phase velocity and coupling impedance are measured and circuit characteristics of the loaded helix are clarif

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730808

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

年代:1990

数据来源: WILEY

摘要:

AbstractSilicon nitride (SiNx) films were deposited by photochemical vapor deposition using a low‐pressure mercury lamp and the dependence of the film quality on the deposition condition was investigated. In addition, a thin‐film transistor (TFT) was formed by the continuous deposition of SiNxand hydrogenated amorphous silicon (a‐Si:H) films.The on/off ratio of the transistor was about seven orders of magnitude and the field effect mobility was 1.4 cm2/V.s. These results indicate that the photochemical vapor deposition is an excellent low‐temperature method for forming films with an excellent interface p

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730809

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

年代:1990

数据来源: WILEY

摘要:

AbstractDevelopment of a high‐frequency, high‐power transistor is expected for communication and broadcast usages. In recognition of superior high‐frequency performance and thermal stability of the lateral power MOSFET, the authors have attempted to improve power and frequency characteristics. By means of the self‐align method using high melting point, 1.5‐μm metal gate, a high‐frequency characteristic of a cutoff frequency of 4 GHz was attained.Since the high output power depends on high breakdown voltage and low on‐resistance, the trade‐off between the breakdown voltage of 100 V and the on‐resistance was carried out using two‐dimensional analysis. Based on the findings, a chip was fabricated which has a saturation output power of 50 W and a drain efficiency of 50 percent at 860 MHz.Further, the output was increased by the parallel operation of multichips containing an internal matching circuit. With three chips, an output power of 100 W, a power gain of 12 dB, and a drain efficiency of 45 percent were attained. With a four‐chip push/pull configuration, an output power of 150 W, a power gain of 12 dB and a drain efficiency of 47

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730810

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

年代:1990

数据来源: WILEY