摘要:

AbstractSeveral investigations on error‐diffusion methods using raster scan for computer‐generated holograms have been described in the literature. However, very little is known about the influence of the procedure applying the Peano curve to computer‐generated holograms. This is because the Peano curve has become effective in recent years in connection with related fields of application.In this paper, the error‐diffusion method using the Peano curve is discussed in detail for the improvement of reconstructed images with computer‐generated holograms. It is clarified under the limitation of area of noise and brightness of images that the error‐diffusion method using the Peano curve gives superior reconstructed images compared with that using

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780301

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe (1, 1) Fadé approximant operator is applied to the fast Fourier transform beam‐propagation method (FFT‐BPM). The Fadé operator for FFT‐BPM is derived, and its relation to the wide‐angle and paraxial operators is investigated. Next, the propagation error of the fundamental mode of a straight step‐index waveguide is evaluated by the mode mismatch loss. It is proved that, in contrast to the wide‐angle operator, Fadé operator does cot exhibit loss, even at small transverse grid‐widths. Finally, as an example of when transverse propagating waves cannot be neglected, the problem of fundamental mode propagation in a tilt waveguide is investigated. It is clarified that the Paé operator preserves an accuracy comparable to that of the wide‐angle operator, even if the tilt angle is widen

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780302

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

年代:1995

数据来源: WILEY

摘要:

AbstractRecently, there has been increased research on millimeter‐wave regions due to mobile communication. In addition to the characteristics of high‐frequency carrier, an even larger‐capacity communication becomes possible by making the communication circuits and the antennas broadband.This paper describes a high‐frequency broadband printed antenna necessary for a monolithic small and lightweight transceiver capable of a large‐capacity communication. As a broadband antenna, a two‐arm spiral antenna was designed and tested at 90 GHz. At frequencies from 89 GHz through 99 GHz, the antenna pattern and the return loss were measured. In addition, Hallen's integral equation for a linear antenna with an arbitrary shape was analyzed numerically by means of the moment method so that the difference between the theory and the measurement was verified. Agreement of both is excellent. Hence, the fundamental data have been collected for realization of broadband active integrated antennas which combine the monolithic circuit and the pla

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780303

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

年代:1995

数据来源: WILEY

摘要:

AbstractA multilayer monolithic microwave integrated circuit (MMIC) directional coupler is proposed in which the characteristics of the multilayer MMIC structure constructed with conductors and dielectric films on a GaAs wafer surface are used effectively. In the proposed directional coupler, a tight coupling of 3 dB can be realized with low loss and in a small area. It is highly flexible in design. Also, it is shown in this paper that by means of the proposed multilayer directional coupler, a millimeter‐wave variable attenuator, a balanced modulator, and an endless phase shifter can be realized. These structures play important roles as millimeter‐wave amplitude/phase control circuits. Hence, it is significant to accomplish miniaturization and MMIC realization.The multilayer directional coupler designed and fabricated in the 40‐GHz band exhibited a circuit area of 0.45 mm2and coupling losses of 4.0 ± 0.2 dB. The designed and measured values agree well. Further, the amplitude/phase control circuits were designed and also exhibited a good perfo

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780304

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper describes a design method in the millimeter‐wave frequency region for an aperture‐coupled microstrip antenna which unifies a feed network consisting of a monolithic microwave integrated circuit (MMIC) which affects the antenna characteristics at millimeter‐wave frequencies, the shift of the location of the radiating element which is important in actual configuration in the millimeter‐wave region, and the effect of the adhesives. Based on this design, an antenna was fabricated. A quartz substrate was used for the radiating element, while a GaAs substrate was used for the feed network. A high radiating efficiency of 87.1 percent and a wideband characteristic of 3.1 percent with VSWR<2 were attained. As an application of this structure, a test fabrication is reported on the aperture coupled microstrip antenna in the 40‐GHz band in which an MMIC frequency converter is i

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780305

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

年代:1995

数据来源: WILEY

摘要:

AbstractTo realize a high‐capacity wireless access, the millimeter‐wave frequencies have been investigated. Research on indoor multipath propagation has been pursued intensively.This paper proposes an evaluation method for the millimeter‐wave indoor high‐capacity digital transmission characteristics. First, the broadband propagation characteristics under indoor multipath environment were measured so that the multiple‐wave configurations are clarified.Next, to quantify the digital transmission characteristics under the multiple wave environment, the level ratio (D/U) of the desired wave to the interference wave was evaluated for a bit error rate of 10−4by means of a 4 PSK‐100 Mb/s and a multipath fading simulator. It was found that the bit error rate is determined by the level ratio (D/UT) of the desired wave to the total interference waves and not by the delay time of the interference wave if the delay time of the interference wave exceeds the symbol duration and that the desiredD/UTapproaches the signal‐to‐noise (S/N) ratio (N: Gaussian noise) giving such a bit error rate. From the foregoing results, this paper proposes a channel design method using theD/Uin indoor high‐capacity wir

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780306

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

年代:1995

数据来源: WILEY

摘要:

AbstractTwo optical waveguides comprising a directional coupler, approach each other gradually through curved waveguide sections from the input ends where the two are sufficiently distanced with negligible coupling. After the coupling section where the two waveguides are placed in parallel, the two are separated again through curved sections to the output ends where they are sufficiently distanced with negligible coupling.In the treatment taking into account the bends of the waveguides, the optical waves propagating through the two waveguides are approximated for simplicity by a superposition of the even and odd local normal modes. The coupling between the guided modes and the radiation wave at the bends often is neglected.In this paper, the method proposed by Sawa for the analysis of the coupled mode equation taking into account the coupling between the guided modes and the radiation modes in the waveguide system including the curved sections is used for the analysis of the directional coupler including the curved sections. The coupling length and power transfer rate are computed for the directional coupler with curved sections represented by a linear function, a cosine function, and a hyperbolic tangent function. The numerical results indicate that the radiation loss is the smallest and an excellent power transfer rate can be obtained if the shape of the curved section is a hyperbolic tangent function.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780307

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper describes the configurations and properties of receptacle User diode modules for optical subscriber networks. In optical assemblies where a single mode fiber is coupled using a ball lens, internal reflection frequently takes place. To reduce the back reflection at the fiber end face, a glass plate physically contacted the head of a PC‐polished ferrule. Then the method to evaluate the physical contact between the fiber end face and glass plate was discussed. Inspection with a Newton ring has proved such physical contact to be an efficient method of assembling a glass plate. In addition, modules were fabricated applying the projection and YAG laser welding, both of which are advantageous in firmly coupling components. Then the stability of the output of modules at higher temperatures, the stability of the contact between the module and PC‐FC connector and the influences of temperature cycling and high‐temperature environment on the connector were investigated. It was found that the change in the optical output was small when the temperatures were 0, 25, and 85°C and that the optical output was stable after temperature cycling and a high‐temperature stress test. Therefore, it was concluded that this receptacle laser diode was suitable for the optical subscriber

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780308

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

年代:1995

数据来源: WILEY

摘要:

AbstractThree‐dimensional (3‐D) analysis of an intersec‐tional optical switch is performed using the finite difference beam propagation method (FD‐BPM), and design guidelines are obtained from this analysis. The operating characteristics of the switch are evaluated by extinction ratio and power attenuation in two output ports. The optimal structure parameters, such as normalized frequency (V), waveguide relative refractive index difference (Δω), and intersecting angle (θ), are obtained for 1.55 μm wavelength operation. Wideband operation in the 1.3 to 1.6 μm wavelength range is discussed taking into account the wavelength dispersion of materials. It is found that to achieve an extinction ratio that is better than 20 dB, a refractive index variation of 0.5 percent is enough for single‐wavelength operation; however, a refractive index variation larger than 0.7 percent is required at the longer‐wavelength side for wideband operation. Finally, the results of 2‐D and 3‐D analyses are compared and good agreement is obtained with an

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780309

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

年代:1995

数据来源: WILEY

摘要:

AbstractAs a simple method for evaluating the reflection and transmission characteristics of a grating waveguide, an analysis procedure is proposed and formulated that is a combination of the coupled‐mode theory and the finite‐element method. The finite‐element method is used for the determination of the coupling coefficients in the coupled‐mode equations. Therefore, the present method is capable of analyzing a grating waveguide with an arbitrary shape. In addition, the energy storage effect of the nonpropagating modes is automatically included. Specifically, an index‐modulation type grating reflector is analyzed so that the validity of the method is confirmed. Also, the present method is applied to the design of a grooved grating reflector so that its usefulness is dem

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780310

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

年代:1995

数据来源: WILEY