摘要:

AbstractA new tetrahedral element is proposed for the finite element analysis of a three‐dimensional resonator problem. It has been reported that in finite element analysis with the conventional tetrahedral elements, nonphysical spurious solutions are generated. In the tetrahedral element proposed here, only the components of electric or magnetic field along the element surface are used as unknown parameters. It is shown that there are many zero eigenvalues in the finite element expression obtained by the new tetrahedral elements. It is demonstrated that the matrix in the new method can be regularized with the eigenvectors corresponding to the zero eigenvalues so that a substantial reduction of the unknown parameters can be realized. The regularization process is purely mathematical. No eigenvalues and eigenvectors are altered. From the eigenvalues obtained from actual numerical calculations for a resonator, it is shown that several of the smaller ones correspond to the resonant modes, and no spurious solutions appear. A feature of the present method is that the spurious modes can be eliminated and the number of unknown parameters is reduced substantially. The method is expected to be an effective analysis method for finite element solutions of three‐dimensional resonator probl

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720301

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

年代:1989

数据来源: WILEY

摘要:

AbstractFollowing a previous report [1], this paper describes the geometrical optics theory applied to waveguides. The ray theory to be used as a foundation is based on the Maupertuis principle. It has been pointed out that the theory is not the one based on Hamilton's principle. Both theories are different in concept. However, the difference in the ray trajectory appears only in anisotropic media. In this paper, the anisotropic medium is assumed to be uniform along the waveguide axis whereas it is inhomogeneous in the cross section. Hence, the conventional isotropic waveguides are included in the present theory. The objective of the paper is to construct geometrically the field of the eigenmode propagating in such a waveguide. Since the construction method for the phase of the field has already been reported, the field amplitude is derived mainly from geometrical considerations. Since some examples coincide with the known results obtained from the field theory, it is presumed that the geometrical interpretation of amplitude holds, in general. New geometrical formulas that cannot be derived from the solutions of the wave equation are obtained.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720302

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe dome antenna has been proposed for scanning an antenna beam at a high speed in a wide angular range. For the design of a dome antenna, an electromagnetic analysis in the concave side of the conducting sphere is required. In connection with this problem, the electromagnetic field by an electric dipole placed on the concave surface of an open conducting sphere has been reported and analyzed in terms of the sum of the whispering gallery (WG) modes, continuous spectrum and ν = 0 (ν: wavenumber in the θ direction) by the authors. However, it has been pointed out that this expression has a problem for an arbitraryka, although it provides a valid result forka=nπ/2 (k: wavenumber,a: sphere radius,n: integer). It is also unattractive numerically since Legendre functions must be calculated by numerical integration. In this paper, an engineering application is attempted by using a high‐frequency approximation. By means of the approximate asymptotic solution and the previous expression, actual numerical calculations have been carried out. By way of comparison with experimental results, the validity of each expression is confirmed and its range of applicability is st

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720303

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

年代:1989

数据来源: WILEY

摘要:

AbstractSince a power MOS‐FET has a reverse diode located internally between the drain and source, when a PWM inverter is constructed with MOS‐FETs, a shunt phenomenon occurs between the upper and lower arms due to the recovery current of this internal diode. This phenomenon can effectively be prevented by limiting the current rise by an inductance. In this work, a PWM inverter with around 1 kW has been realized which operates with a high carrier frequency of about 100 kHz by using a close‐coupled inductor. Furthermore, as a design guideline for a PWM inverter, an analysis is made of the loss of each device and inverter efficiency and the experimental results are com

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720304

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe Walsh transformation is a useful method which can replace the Fourier transformation for analysis of alternating‐numbers, and is suitable for digital waveform analyses. Since this is a binary transformation, its hardware realization is achieved easily. Using this advantage, this paper proposes a discrete Walsh‐transformation circuit using a switched‐capacitor circuit. This paper also proposes a solution of a problem of the change of power spectrum due to the phase‐shift of the input signal which prevents practical applications of the Walsh transformation to an electronic circuit. In the proposed circuit, a Walsh‐function wave based on a rectangular waveform synchronized with the input signal is formed, and this is used for the clock of the switched‐capacitor discrete Walsh‐transformation circuit. This arrangement makes the signal‐detection period variable so that the signal is always processed with no phase shift. This arrangement itself is also suitable for a switched‐capacitor circuit. A prototype switched‐capacitor discrete Walsh‐transformation circuit (for 32 sampling points) was made with discrete components. The results confirm that the proposed method is effective for analyz

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720305

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe optimum deposition conditions of (Hf·Ti)C film on cemented carbide tools using low‐pressure chemical vapor deposition are discussed here based on evaluations of the physical and mechanical properties of the deposited films.The film composition could be controlled through the flow rate of titanium and hafnium iodides and the film formed had a Vicker's hardness of 2500 to 3000 kg/mm2. The wear resistance of the (Hf·Ti)C coated tool was as high as that of the previously developed HfC coated tool. The grooving wear of the (Hf·Ti)C coated tool was higher than that of the TiC coated tool. This was attributed to the larger thermal expansion coefficient of the (Hf·Ti)C film compared with those of TiC an

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720306

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

年代:1989

数据来源: WILEY

摘要:

AbstractTo decrease the insertion force of multipin electrical connectors in communication equipment, the tip shape of the male connector was analyzed theoretically, and a model experiment of contact insertion was carried out. From comparison of the theoretical and experimental results, the following results were obtained: (1) if the friction between contacts in connector insertion is not taken into account, a root curve shape is the optimum tip shape; and (2) the insertion experiment using a model for a male connector tip agrees with the theoretical result. As a result, it was shown that the friction between the contacts has an important role, and that to reduce the insertion force, the shape of the tip must be designed with friction taken into account.From the foregoing results, the connector tip was designed to make the insertion force constant regardless of friction. By investigating the force reduction using a multipin connector of about 200 pins, the evaluation based on the tip shape was found to be valid.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720307

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

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper describes the design and performance of a programmable optical demultiplexer which can compensate the influence of: (1) scattering in the wavelength of an optical source; and (2) wavelength fluctuation of the optical source caused by temperature change, by controlling the branching characteristics in accordance with the wavelength of the optical source. In this multiplexer, a 32‐element Si photodiode array was used to carry out programmable control of the branching characteristics. This optical demultiplexer has the following merits: (1) a wide channel passband is not needed; and (2) since the passband‐center wavelength of this multiplexer is adjusted to the wavelength of the optical sources, fine tuning of the branching characteristic in fabrication is not needed. The fabricated programmable optical demultiplexer has a channel wavelength spacing of 4.0 nm, an insertion loss of 8.0 dB which includes a loss of 3.9 dB due to the detection loss caused by the gap between two photodiodes composing the PD array, and a passband width of 2.8 nm. It was confirmed also by a digital transmission experiment (32 mB/s, RZ signal) that this demultiplexer can maintain its optimum branching characteristics for any wavelength deviation in the optical sour

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720308

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

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper investigates the measurement method of optical fiber offset in two directions by one‐directionally observed image. This method employs the transmitted illumination and the bright lines of the intensity distribution due to the lens effect of the fiber are used to observe the position. The method is advantageous because of a simple mechanism for its realization. The observation principle of fiber position is investigated based on computer simulation and experimental results to clarify characteristics of the method. The real measurement of the fiber offset and its precision is investigated for fusion mass‐splicing, to which the present method is very suitable. Employing this method, the standard deviation of 1.3 μm is achieved in precision of the measurements of the fiber offset. The screening characteristics for a given offset are also evalu

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720309

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

年代:1989

数据来源: WILEY

摘要:

AbstractA slot‐coupled directional coupler is proposed and analyzed. In the slot‐coupled directional coupler, microstrip lines set on both sides of a common ground plane are coupled through a slot in the common ground plane. This coupler can easily realize a tight coupling such as 3 dB with a small physical size. This paper shows that it is possible to form a planar multiport directional coupler with 2n(n: integer) input or output ports without line crossings by combining slot‐coupled directional couplers. Using such a planar multiport slot‐coupled directional coupler, a multiport power amplifier and a BMN (Butler matrix network) can easily be formed in a small physical size.The 3‐dB slot‐coupled directional coupler fabricated for trial has a coupling of 3.2 ± 0.2 dB, a return loss of more than 25 dB, and an isolation of more than 28 dB in the frequency range offO±20 percent (fO= 1.5 GHz). These measured values agreed well with

ISSN:8756-663X    

DOI:10.1002/ecjb.4420720310

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

年代:1989

数据来源: WILEY