摘要:

AbstractThis paper deals with a circuit in which a total of eight ports made of two sets of four ports are mutually separated and in which the input from one port is delivered to four ports of another set with equal amplitudes with a certain phase relationship. This circuit is called the eight‐port hybrid circuit and is an extension of the characteristics of a conventional (four‐port) 3‐dB hybrid to the case of eight ports. A circuit configuration is proposed by means of four branch‐line‐type 3‐dB hybrids.First, by taking advantage of the symmetry of the circuit, an analysis is carried out. the relationship to be satisfied by the characteristic admittances of each branch line is determined. the frequency characteristics of the scattering matrix elements are presented.Next, a design method for broadening the bandwidth is given for the matching circuits to be attached to each port and quarter wavelength transmission lines connecting each hybrid. A relative bandwidth of about 20 percent is realized. Also, the test circuit is measured and the validity of the design method is confirmed. the present circuit is advantageous in that the circuit configuration is possible on one side of the substrate by means of strip lines and all eight ports are directed outward so that connection with other circuits is

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770801

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper considers the problem of scattering of electromagnetic waves by a strip conductor when the source is a line current source or a line magnetic current source. the problem is analyzed as a two‐dimensional boundary value problem when the strip conductor thickness is negligibly thin and the distance from the center of the strip to the source is larger than one‐half its width. the expansion functions of the current are selected to satisfy the edge condition. By means of the spectral domain method, the simultaneous equations for the expansion coefficients and the specific expressions for the coefficients are derived. the current distributions and the scattered far field are computed numerically. In the analysis process, it is shown that the coefficients derived are identical to those of the simultaneous equations in the analysis for the plane wave incidence making use of the Weber‐Schafheitlin discontinuous int

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770802

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

年代:1994

数据来源: WILEY

摘要:

AbstractA 1.3‐μm InGaAsP/InP laser diode (LD), a 1‐μm InGaAs/GaAs LD, and a 0.65‐μm GaInP/AlGaInP LD were fabricated using Cl2reactive ion beam etching. Four desirable features of dry etching, i.e., smoothness, controllability, uniformity, and capability of fine pattern formation, were investigated through the fabrication of these devices. the morphology of dry‐etched InP generally is not as good as that of GaAs; but, nevertheless, we achieved very smooth InP etching with a roughness of only 1.4 nm. the InGaAsP/InP LD made using this etching had a threshold current of 20 mA, which is as low as that of a wet‐etched LD. Precise control of etching depth is necessary for AlGaInP‐LD fabrication, and ion‐current monitoring made this possible with an accuracy of 22 nm. the deviation of AlGaInP etching depth is only 15 nm across a 2‐inch wafer. This good uniformity resulted in a small deviation of threshold current fabricated in 2‐inch form. an InGaAs/GaAs vertical‐cavity surface‐emitting laser array having uniform threshold current was fabricated making use of the capability of fine pattern formation, and the record low‐threshold current of 190 μA was achieved in an air‐post VCSEL etched by rea

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770803

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

年代:1994

数据来源: WILEY

摘要:

AbstractReceiver optoelectronic integrated circuits (OEICs) have been successfully designed on a three‐inch diameter InP substrate. Epitaxial layers grown by OMVPE on three‐inch diameter InP substrates showed good uniformity of electrical and optical properties. By using the epitaxial layers, transimpedance‐type receiver OEICs were fabricated. the receiver OEICs over a three‐inch diameter InP substrate showed an average bandwidth of 2.78 GHz with a standard deviation of 280 MHz. the receiver also exhibited a transimpedance of 61.1 dB and a sensitivity of ‐24.9 dBm for 2.4 Gb/s input signals. These results indicate that the receiver OEICs designed on a three‐inch diameter InP substrate are ready for practical use in Gb/s lightw

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770804

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

年代:1994

数据来源: WILEY

摘要:

AbstractAn integrated coupling device between a GaAs/Al‐GaAs laser diode and an optical fiber using a microlens is described. It is calculated that the high single‐mode fiber coupling efficiency of 81 percent is obtained for the microlens with RMSA of 0.4 λ and that the large alignment tolerance of 55 μm is obtained in thez‐direction. It is demonstrated experimentally for single‐mode fiber coupling that the coupling efficiency is 26 percent and that the alignment tolerance in thez‐direction is 19 μm. the differences in the coupling efficiency and alignment tolerance between the calculation and experiment are due to a mismatch of beamwidth and the fabrication error of the fiber guide. Additionally, measurement of the oscillation spectrum of this coupling device, which has a composite cavity, showed that an LD with a microlens and fiber causes multimode oscillation due to reflection from the

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770805

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

年代:1994

数据来源: WILEY

摘要:

AbstractAn analysis program is developed to evaluate the readout ability of the direct‐contact type linear‐image sensors that do not possess the image‐forming optical systems. It is used exclusively to evaluate the readout characteristics of the direct‐contact type linear‐image sensors. the program deals with the sensors with multi‐layer structures parallel to theXYplane of the 3‐D (and mutually orthogonal)XYZcoordinate system. the optical path of the illuminating light emerging from the source, attenuations at the boundaries between different materials and the lights blocked by the electrode and the receiver are calculated if they are used in determination of the illumination distribution in theXYplane. the calculation procedure comprises two parts: the illumination on the document plane due to emerged light from the source, and the reflected light from the document onto the sensor. This program takes not only document plane reflections into account but can also factor in the reflections caused by light penetrations into the document paper (Yule‐Nielsen effect). Investigations using this program show that the resolution of the read‐out function of direct‐contact type sensors strongly depends on the distance from the document to the receiver and the q

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770806

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn a conventional‐type astable multivibrator, the upper limit of the division ratio for stable dividing operations is at most 1/20. In this paper, we propose and analyze a frequency divider based on the Miller integral‐type switched capacitor (SC) astable multivibrator that maintains stable operation even with a large dividing ratio.This divider has a circuit configuration in which the state reversal occurs at a point during the straight fall of the output voltage waveform of the Miller integrator in a stepwise fashion. Therefore, the divider is not affected by either supply voltage or external noise. the dividing ratio can be varied in a much larger range than that of the conventional type simply by changing the value of the capacitor. the mathematical formula can be expressed simply with only circuit parameters. the computed values and the measured values agree well.Also, since no trigger generator is needed (as is the case with a conventional type), the dividers can be cascaded easily. the resultant dividing ratio is the product of the individual dividing ratios. Further, by using two sets of modifications of this divider and by using one of them as the feedback circuit, a pulse number converter can be realized in which the ratio of the input pulse number and the output pulse number can be varied arbitrar

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770807

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe error‐rate performance of the partial response maximum likelihood (PRML) system combining the partial response (PR) system with the Viterbi decoding, which is a type of maximum likelihood (ML) decoding, is investigated in perpendicular magnetic recording using a multilayered main‐pole head. Waveform approximation is carried out with regard to the isolated reproducing waveform obtained by experiment; and, based on this, the bit error rate is determined by computer simulation.First, taking into account the noise increase due to equalization, the signal‐to‐noise ratio (SNR) at the discrimination point and the bit error rates of bit‐by‐bit decoding of several PR systems using the characteristics of the multilayered main‐pole head are determined. Next, the bit error rates of the PRML system are determined for these PR systems and then compared with those for the conventional PR system. Then it is clarified that the best performance is obtained by the PR(1, 0, 0, 0, ‐1) system among these PR systems, and the improvement of SNR compared with the conventional PR system is about 1.9 dB in the case of the bit‐by‐bit decoding system and 4.1 dB in the case of the PRML system at an

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770808

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe small‐signal ac dynamic characteristics of the voltage‐resonant converter controlled by multiple resonant switches are analyzed, the resistances of the switches and diodes, equivalent series resistances of the resonant inductors and capacitors are taken into account, and numerical calculations utilizing the state transition matrix are applied. Analytical and experimental results are in good agreement, and the effects of parasitic resistances and filter elements on dynamic characteristics are clarif

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770809

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn this paper, the radiation characteristics and its analysis method are discussed for a polyhedron‐approximated reflector antenna in which the reflector is made of several planar facets as in a large deployable antenna. Based on the current distribution method considering the law of reflection and the effect of diffraction, the aperture integration method using the ray tracing containing an approximation in the law of reflection is used for the electric field distribution of a polyhedron‐approximated antenna. It is found that the electric field of the present antenna becomes maximal at the joint between the facets. It is shown that the far‐field characteristics of the antenna derived by the aperture integration method based on the approximate ray tracing and by the current distribution method are identical. the relationship was found between the equivalent aperture plane where the field distributions derived by the two methods are identical. Further, by means of the rigorous ray tracing method, the three dimensional ray behavior is shown. It is found that the aperture integration method based on the rigorous ray tracing method is inappropriate for the calculation of the radiation characteristics of the present an

ISSN:8756-663X    

DOI:10.1002/ecjb.4420770810

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

年代:1994

数据来源: WILEY