摘要:

AbstractThe reproducing process of perpendicular magnetic recording is here analyzed by a finite element numerical simulation. A mechanism is found for significant improvement of reproduction sensitivity by means of a soft magnetic layer backing a CoCr medium. The analysis is conducted for a vertical head consisting of main and auxiliary magnetic poles. The magnetic field saturation and reduction are taken into account in iterative calculation based on the Newton‐Raphson method. In calculation of the magnetic field reduction a measured M‐H loop for CoCr including the minor loop is used. It is found that the soft magnetic backing layer increases by an order of magnitude the amount of magnetic flux flowing deep into the main pole. This finding confirms experimental observation that the reproduction output increases by an order of magnitude with the backing layer. The paper also describes the spacing loss in reproduction of perpendicular recording. A more useful definition of reproduction efficiency of the head is found from the above results. The computation procedure is useful in analysis of a nonlinear reproduction proc

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700501

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe ringing choke converter is widely used as an electronic power supply with a small capacity. A number of works have been published on the feedback systems for adjustment of output voltage. No sufficient analysis, however, has been undertaken on the static and dynamic characteristics. In this paper, a nonlinear differential equation describing the basic operation is first derived. Next, from a small signal model obtained from this differential equation, a loop transfer function of the converter is derived. Further, the transfer function for an input variation and a load variation under regulation have been derived. As a result, the characteristic equation becomes linear and it is shown that the converter is extremely stable. The dynamic characteristic parameters of the ringing choke converter are found different from those of the conventional reactor current discontinuity mode converter. Both the gain bandwidth product of the loop transfer function and that of the transfer function of the output voltage fluctuations for the input voltage fluctuations under regulation are smaller in the ringing choke converter than in the reactor current discontinuous mode converter. It is found that the ringing choke converter is less susceptible to the input voltage fluctuations and operates with a greater stability than the reactor current discontinuous mode converter.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700502

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe existence is found for coupled guidedand surface polariton‐modes, in a slab‐type waveguide with a silver thin layer on top of it. The phase‐matched condition for the second harmonic generation (SHG), due to the fundamental and surface polariton modes, is determined. In waveguides of this structure, the realization of long propagation‐length (i.e., long interaction‐length) is possible in a waveguide with energy storage (Corning glass 7059), to compensate for the losses due to excitation of plasma polaritons. The generation of the phase matched second harmonics due to the surface polaritons is experimentally observed. The waveguide is tapered perpendicular to the direction of propagation. The theoretical phase matched condition between the fundamental and second harmonic waves is determined for a specific silver thickness on top of the slab waveguide. This phase‐matched condition is confirmed experimentally. The output of aQswitchedNd: YAG laser is used as the funda

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700503

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe experimental results of the optical response characteristics of GaAs MESFET photodetectors were analyzed numerically, using the optical response mechanism of the FET. The device used was designed for the X‐band applications and the numerical analysis was carried out mainly on the IV characteristics. As a result, the experimental results were explained successfully by taking into account the influence of the optically controlled channel curren

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700504

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

年代:1987

数据来源: WILEY

摘要:

AbstractA Josephson timed regulator has been designed and tested which supplies timed bias current to logic gates, such as EX‐OR and NOT gates. This regulator consists of four SQUIDs in series, where the output line is coupled twice to each SQUID. In addition, this output line functions as the SQUID control line. As a result, all SQUID junctions are able to simultaneously switch even if the junction critical current is scattered. This regulator is fabricated using Pb alloy technology, successfully tested, and then favorably compared with computer simulation result

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700505

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe Josephson junction is an oscillator driven by constant current. Therefore, the integrated device of the weak‐link type Josephson junction for detecting electromagnetic waves using the junction as a local oscillator can be considered. The superconducting device proposed by Likharev based on this concept is the Josephson triode consisting of three Josephson junctions. This paper describes the analysis of the Josephson triode which is the superconducting device for the heterodyne detection. First, the static characteristics are analyzed by use of the equivalent circuit and the fundamental equations. The necessary conditions for the normal resistances are derived. It is shown by numerical analysis that the millimeter wave heterodyne detection characteristics of the triode are identical with the theory and experiment for a tunnel junction. Moreover, the results analyzed numerically can be explained by analytical considerations and the simplified equivalent circuit of the Josephson triode is derived. The relations between the intermediate frequency output power and the local oscillator power are represented analytically via the simplified equivalent circuit of the triod

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700506

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

年代:1987

数据来源: WILEY

摘要:

AbstractBeta‐phase silicon carbine (β‐SiC) layers have been grown on silicon substrates at a growth temperature of 1000°C and at a low pressure of 200 Pa from an SiHC13‐C3H8‐H2system. Silicon substrates are 4‐inch silicon wafers, and (111) tilted substrates with 4° off‐axis and (100) substrates with no off‐axis are both used. It was found from X‐ray diffraction and reflection high‐energy electron diffraction (RHEED) analysis that β‐SiC single‐crystal films are obtained on (111) tilted substrates, but not on (100) substrates under the conditions used in this experiment. By forming an n‐p heterojunction between a P‐doped β‐SiC layer and a p‐type substrate and measuring its rectifying characteristics, the saturation current density at 2 V in the reverse‐biased region

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700507

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

年代:1987

数据来源: WILEY

摘要:

AbstractTo calculate the reflection/transmission characteristics of a dielectric slab waveguide with finite periodic corrugation, a numerical approach based on the finite‐element method is proposed. Although the finite‐element method has already been applied to discontinuity problems in dielectric waveguides, it was virtually impossible from the viewpoints of computation time and computer capacity to apply the finite‐element method directly to a waveguide with many discontinuities such as a finite periodic waveguide. In the present article, a “substructure” has been introduced to the finite‐element formulation to treat a large number of discontinuities. Consequently, the interaction of surface waves and radiated waves among all discontinuities is automatically taken into account. Also, an unbounded waveguide is replaced by a corresponding bounded one; this creates a problem where an artificial boundary should be set. It was found that in a finite periodic waveguide, a good approximate solution can be obtained by choosing the position of the artificial boundary with an adequate distance from the waveguide, since the dependence of the solution on the position of the artificial boundary is not significant. The validity and usefulness of this method was confirmed by comparing the numerical results with the values obtained from other theoretical methods and the experime

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700508

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

年代:1987

数据来源: WILEY

摘要:

AbstractAlthough Luneburg lenses are already in practical use, few papers have been published on their wave‐optical analysis. This is due to the difficulty in the wave‐optical analysis of the electromagnetic field in an inhomogeneous medium with a large radius, in addition to the fact that most researchers have been interested so far in a geometrical‐optic analysis. Increased applications of this type of lens to a microwave band require more precise analysis from the wave‐optics viewpoint. This paper deals with the wave‐optical analysis of a cylindrical Luneburg lens. Taking several numerical analysis methods, the relationship between the number of terms of a truncated series and the accuracy of the analysis, and the relationship between the computation time and the accuracy of the analysis are examined. A method is proposed which can be applied to a lens having a large radius compared with the wavelength. By using this method, actual numerical analyses are carried out, and the focus characteristics and the distribution of the heat generation (the power dissipation density) in the lens are shown. These are compared with the results of published numerical analyses. Some interesting results, which cannot be obtained from a conventional geometrical‐optic analysis, are obtained by the prop

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700509

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

年代:1987

数据来源: WILEY

摘要:

AbstractWith a view to high‐speed operation of a power clock, a power supply circuit with a high cut filter is proposed. The harmonic noise generated by the nonlinearity of the regulator distorts the sinusoidal current as the clock speed is increased and hence the duty factor is degraded. Hence, it is important to eliminate this noise. The filter has a function to pass the fundamental sinusoidal wave but stop the harmonic noise generated at the regulator. First, the determination of filter parameters is described. It is demonstrated by a computer simulation that the filter is extremely effective at a high frequency. Next, a three‐dimensional high‐density model has been fabricated and the output current waveform of the regulator at 400 MHz (machine cycle time of 1.25 ns) has been measured. By means of this measurement, the validity of the approach is demonst

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700510

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

年代:1987

数据来源: WILEY