摘要:

AbstractCarrier density dependence of the detection abilities of an antenna‐coupled point‐contact Ge diode at 118 μm and 10.6 μm was studied. The optimum carrier densities obtained by experiments were 1016cm−3and 2 × 1017cm−3for CH3OH and CO2lasers, respectively.These results were explained by calculation based on the assumption that the conductivity of the metal is in the relaxation region and that the spreading resistance of the semiconductor is affected by the skin effect, carrier inertia and displaceme

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710801

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

年代:1988

数据来源: WILEY

摘要:

AbstractOne method to improve the signal‐to‐noise ratio in a magnetic recording is to use a filter to narrow the frequency bandwidth. This paper presents a theoretical analysis of the influence of a low‐frequency spectrum on reproduced waveforms in the MFM and ZM coding methods, together with the evaluation of possible narrowing of the bandwidth. In this method, a reproduced waveform is constructed by superimposing solitary waveforms according to the code‐words of the MFM or ZM modulation methods. Then low‐frequency spectra were eliminated from the Fourier spectrum of the reproduced waveform, and another waveform is obtained by reconstructing the remaining spectra.The results show the waveform distortions, a change of the amplitude, and peak‐shifts. These are all due to the elimination of low‐frequency spectra. The influance on the design parameters of a disk‐head system (e.g., the length of a gap in its

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710802

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

年代:1988

数据来源: WILEY

摘要:

AbstractSequential‐flash data converters using switched‐capacitor circuits are developed for realizing a given conversion speed with a minimum number of components. Repeatingn‐bit flash conversionmtimes, each converter accomplishes (m x n)‐bit digital‐to‐analog or analog‐to‐digital conversion inmcycles of a clock frequency. An accurate conversion is also possible because each converter is configured such that the offset voltages of op‐amps and parasitic capacitances have no effect on the conversion process. Error analysis shows that a conversion accuracy higher than 8 bits can be expected from each converter if integrated using present MOS technologies. Prototype converters built using discrete components are also given to confirm the princi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710803

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

年代:1988

数据来源: WILEY

摘要:

AbstractWith the widespread use of home video and other equipment, it is strongly desired to realize a high‐frequency monolithic IC active RC filter. This paper proposes a method of constructing the integrator with voltage‐controlled current source operated by a single 5‐V supply. Even though operated by a single 5‐V supply, the proposed integrator can realize a wide dynamic range due to an elaboration in the output circuit. For a cutoff frequency of 1 MHz, the maximum input voltage for distortionless output voltage is 1.0 VP‐P. By a simple compensation, an excellent high‐frequency characteristic exceeding 2 MHz is obtained. The proposed integrator is of a variable characteristic with differential inputs, and, consequently, an automatically tunable leapfrog‐type filter can be realized. To evaluate the performance of the proposed integrator, a high‐frequency analysis and a computer simulation were made. The integrator was realized as a monolithic IC by the general‐purpose process for home‐use equipment, and the automatically tunable filter was constructed. The experimental result agreed well with the theory, indicating that the whole filter can be realized

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710804

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper investigates the dispersion characteristics and bending loss of dispersion‐shifted fibers with dual‐shaped core and α index. It is seen that the bending loss of dual‐shaped core dispersion‐shifted fibers can be smaller than those of α‐index fibers at a fixed condition of splicing loss. The possibility that the bending characteristics of the fiber is as good as or even better than that of conventional single‐mode fibers is indicated. It is also understood that the dual‐shape core dispersion‐shifted fibers are superior to the conventional ones in dispersion sensitivity. Further, it is shown that there is an inverse relation between the dispersion slope and the dispersion sensitivity. The dispersion‐shifted dual‐shaped core fiber was fabricated and its propagation characteristics were measured to confirm its superior performance. The design parameters of dispersion‐shifted fibers for practical uses are given together with typical examples. It is shown that in the practical range, the fiber parameters are determined by the mode field diameter and

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710805

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

年代:1988

数据来源: WILEY

摘要:

AbstractA microwave power combiner with waveguide ports is proposed and its design method is described. It can combine a large number of inputs at the same time and its voltage tolerance is high. On the side wall of a circular TM0m0(m= 2, 3, 4,…) mode resonator, rectangular waveguides are connected as the input terminal while a circular waveguide is connected at the bottom surface of the resonator as the output port. The output is transformed into a rectangular waveguide via a TM 01ô‐TE 10□mode transformer.Slits on the side of the output circular waveguide prevent propagation of the modes that do not contribute to the power combining. In the design method, theYparameters are computed from the equivalent circuit seen from the output side. Thus, the matching condition is obtained from the image parameters. Actual dimensions of the iris for adjustment of the coupling between the input and output waveguides and the resonator can be found from this procedure. The insertion loss of a 14‐GHz four‐way combiner with a TM020mode resonat

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710806

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper describes a Lamb wave device for quadrature phase shift keying (QPSK) systems. By way of numerical calculations, it is found that the zeroth‐order symmetric mode Lamb wave in a piezoelectric ceramic thin plate has a low dispersion and a large coupling constant. The signal processing device using this mode consists of four delay lines with different acoustic phase delays on a substrate and possesses three functions: phase shifter, phase comparator, and filter. Experimental results are presented for the Lamb wave device for QPSK modulation and demodulation, and they agree well with the operating principle. The data transmission speed of the basic system for modulation and demodulation is 0.8 Mbit/s at the carrier frequency of 5.6 MH

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710807

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

年代:1988

数据来源: WILEY

摘要:

AbstractA new triangular element is proposed in the vector finite‐element solution of a dielectric waveguide. In the conventional finite‐element expression based on the three magnetic field components, each component is treated independently by continuous elements. The elements used in this paper are subject to the condition that the longitudinal field components are continuous between adjacent elements and the transverse components have tangential components continuous at the element boundary. In this method, as many zero eigenvalues as the number of unknowns of the longitudinal components are generated. However, all the remaining nonzero eigenvalues correspond to the physical modes and no spurious solutions typical in the conventional vector finite‐element solutions are generated. The present elements are suited for representation of the forced boundary conditions, and the analysis region can easily be applied to an arbitrary waveguide. To investigate the validity and effectiveness of the present method, it was applied to a hollow cylindrical waveguide, a dielectric loaded rectangular waveguide, an anisotropic refractive index dielectric waveguide, and a ferrite loaded square wave

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710808

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

年代:1988

数据来源: WILEY

摘要:

AbstractFor a single‐ended dc‐to‐dc converter using a magnetic amplifier, an undesirable setting of the magnetic amplifier during the off‐period is analyzed. It is found that the C and R snubbers are installed on the main switch and on the rectifying diode on the secondary wiring of the transformer discharge during the off‐period of the main switch, and then this discharge current undesirably sets the magnetic amplifier. The undesirable setting quantity increases if a transformer with a smaller magnetization inductance or a saturable reactor with a smaller coercivity is used. Hence, the effect is more pronounced in a converter operated at a higher frequency. The undesirable setting is larger in a converter with a lower output voltage. From these results, a new circuit is proposed in which the coercivity of the saturable reactor can be increased effectively by installation of a winding for flowing the reset current in a magnetic amplifier. It is confirmed that this system can reduce the undesirabl

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710809

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

年代:1988

数据来源: WILEY

摘要:

AbstractAmorphous cobalt ferrite (CoFe2O4) films were formed by a two‐source vacuum evaporation technique, using CoFe2alloy and P2O5as the source materials. It was found that the crystalline phase and perpendicular anisotropy constant (Ku) were dependent on the pressure of P2O5during film deposition. When the pressure of P2O5was higher than 5 × 10−3torr, the film was amorphous. When the pressure of P2O5was higher than 8 × 10−3torr, the film had perpendicular anisotropy. The maximum perpendicular anisotropy constant was obtained (1.8 × 105erg/cm3) when the film was formed under a P2O5pressure of 10−2torr. This value is one order of magnitude higher than that of amorphous nickel ferrite films. The cause of the perpendicular anisotropy is thought to be due to the columnar structure formation of Co2+and Fe2+perpendicular to the film surface. When the amorphous CoFe2O5film with perpendicular magnetization is heat‐treated under the P2O5pressure (Pp2O5) of 10−2torr,Kualso increases with the increase of the treatment temperature;Kuof the amorphous CoFe2O5film with perpendicular magnetization is comparable with those of barium ferrite and single crystalline CoFe2O4films. Therefore, this film can be used for the magnetic r

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710810

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

年代:1988

数据来源: WILEY