Antennas for Japanese terrestrial microwave relay links have been developed since the1950's and put into commercial use up to now in Japan. In particular, the path-length lens antennas developed in 1953 represents a monumental achievement for terrestrial microwave relay links, and the offset antenna for 256 QAM radio relay links developed in 1989 has the best electrical performance in the world. This paper reviews the antennas for Japanese terrestrial microwave relay links that have historical significance and describes the antenna design technologies developed in Japan.

This paper describes a historical review of satellite onboard reflector antenna systems in Japan.

We newly propose an optical coherence domain reflectometry for optical subscriber networks with measurement range enhancement. This reflectometry is based on our own technique to synthesize an optical coherence function. An optical switch after a light source generates optical pulses, which select the measuring region, in which one coherence peak is scanned with high spatial resolution. An optical fiber loop delay line including a frequency shifter is placed in a reference-path of the interferometer. In this method, the measuring region could be easily changed by the hetelodyne intermediate frequency selected at the electronic band pass filter. In the basic experiments, the reflections at 5 km distance are measured with a spatial resolution of 8 cm, and the change of the measuring region is successfully demonstrated.

The fields in the junctions between straight and curved rectangular waveguides are analyzed by using the method of separating variables. This method was succeeded because the authors developed the method of numerical calculation of the cylindrical functions of complex order. As a result, we numerically calculate the reflection and transmission coefficients in the junctions in various situations, and we compare these results with the results by the perturbation method and with the results by Jui-Pang et al.

We design a four-reflector offset antenna satisfying the cross-polarization elimination condition and the broadband characteristics condition which consists of one primary horn, three subreflectors and one main reflector. The cross-polarization elimination condition for the four-reflector offset antennas is expressed by the equations of hyperbolas with the coordinate axes of the reciprocal of equivalent focal lengths. The configurations of the reflector system are derived simply from the graphical representation because four-reflector offset antennas satisfying these relationships exist on the hyperbolas with the coordinate axes of the reciprocal of equivalent focal lengths. Furthermore, we clarified that the derived condition for having planar phase front applying the broadband characteristics condition is independent of frequency. An actual design example for the four-reflector offset antennas satisfying the cross-polarization elimination condition and the condition for having planar phase front, both of which are independent of frequency is shown. The design method using the graphical representation is simpler than that of the tri-reflector offset antennas.

In order to clarify the receiver sensitivity of remote keyless entry systems operating at 314 MHz, the radiation characteristics of a cabin antennas must be studied. For this purpose, electromagnetic simulations are very useful but the multiple reflected waves present in the cabin must be accurately estimated. No prior study examined the radiation characteristics of cabin antennas. This paper introduces an accurate simulation method. A MM (Method of Moments) simulator is selected because it can simulate multiple reflected waves. Initial studies are being performed to find the calculation requirements and ensuring convergence of multiple reflected wave structures. Next, calculation requirements for car analyses such as convergence parameters and computer abilities are studied. The calculation time is 11 hours by a personal computer. 1.1 GB of RAM is also needed. Many calculated results such as three-dimensional radiation patterns and induced currents on the car's body are obtained. The radiation pattern varies with antenna position, and polarization changes are shown. In order to ensure that the results are accurate, measurements are made on a one seventh scale model of a car. The good agreement of measured and calculated results verifies the validity of the simulation method. The influence of multiple reflected waves on the radiation patterns is also experimentally studied. The conclusion is that the MM method is shown to be useful in estimating the radiation pattern of cabin antennas. Interesting calculation results are also shown.

Laser induced boron doping of silicon is studied as a function of the laser pulse number and energy density, in a special configuration where the precursor gas (BCl3) is injected and chemisorbed on the Si surface prior to each laser pulse. In-situ optical diagnostics, based on the transient reflectivity at 675 nm, allow to control the evolution of the dopant concentration and of the doped layer thickness during the laser doping process. Samples are characterized by the four-point probe method, atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS). As the laser pulse number is scanned from 10 to 200 at a constant laser pulse energy, the junction depth increases from 21 to 74 nm while its sheet resistance decreases from 220 to 17 Ω/. Moreover, boron concentrations well above the solubility limit (up to 31021 cm-3 for 200 pulses) and very abrupt box-like dopant profiles are obtained. So, laser doping, in this dopant gas injection configuration, seems to be a very attractive technique to meet the International Technology Roadmap for Semiconductors (ITRS) requirements for ultra-shallow junctions.

The vertical-cavity surface-emitting laser (VCSEL) is becoming a key device in high-speed optical local-area networks (LANs) and even wide-area networks (WANs). This device is also enabling ultra parallel data transfer in equipment and computer systems. In this paper, we will review its physics and the progress of technology covering the spectral band from infrared to ultraviolet by featuring materials, fabrication technology, and performances such as threshold, output power, polarization, modulation and reliability. Lastly, we will touch on its future prospects.

This paper describes the recent progress made in developing wavelength tunable semiconductor light sources for WDM applications. Wide and quasi-continuous wavelength tunings were investigated for a wavelength-selectable laser and a wavelength tunable distributed Bragg reflector (DBR) laser having a super structure grating (SSG). A wavelength-selectable laser consisting of a DFB laser array, a multi-mode interferometer (MMI), and a semiconductor optical amplifier (SOA) demonstrated a quasi-continuous tuning range of 46.9 nm by using temperature control. A wavelength-tunable DBR laser with SSG exhibited a quasi-continuous tuning range of 62.4 nm by using three tuning current controls. Wavelength stabilization was also demonstrated under the temperature variations of 5.

Bidirectional reflection distribution functions (BRDFs) of commercially pure titanium sheets with three different kinds of surface morphology were measured. Those experimental BRDFs were analyzed by using Phong's reflection model. Topographic measurements of the specimens' surfaces were performed with using a stylus-method. An explicit microfacet model based on topographic data was proposed. With using the explicit microfacet model and geometrical optics the calculated BRDFs were obtained and then compared with the experimental BRDFs. Both of them were in a good agreement. Through this comparison physical meanings of Phong's reflection model were discussed. We concluded that with using the explicit microfacet model it will be possible to calculate the BRDF of the materials' surface in arbitrary illumination conditions and that this modeling will be useful to develop new aesthetic surface appearance in material industries, computer graphics, architectural design and surface science.

We propose an efficient, low cost, multicast ATM switch which is fair to all inputs. The switch consists of a novel copy network which creates unicast packets in a fair manner, followed by a network that routes packets to their correct Address Translation Tables (ATT's) and ultimately a unicast routing network which ensures sequencing. The copy and routing networks are based on deflection routing. We show that our switch requires O(log N) stages and can be designed for any arbitrarily low level of packet loss. The theoretical results are backed up by simulations. Switching elements in both the copying and routing networks have O(1) bit complexity, making the overall bit level hardware complexity of the network O(N log N). The latency of the switch is proportional to the number of stages O(log N). Unlike other existing copy networks, our copy network drops packets in a fair manner and hence can provide quality of service (QoS) support. The switch is output queued and allows the delivery of multiple packets to the same destination during a time slot.

This paper describes the adaptability of communication software through a biologically-inspired policy coordination. Many research efforts have developed adaptable systems that allow various users or applications to meet their specific requirements by configuring different design and optimization policies. Navigating through many policies manually, however, is tedious and error-prone. Developers face the significant manual and ad-hoc work of engineering an system. In contrast, we propose to provide autonomous adaptability in communication endsystem with OpenWebServer/iNexus, which is both a web server and an object-oriented framework to tailer various web services and applications. The OpenWebServer's modular architecture allows to abstract and maintain a wide range of aspects in a HTTP server, and reconfigure the system by adding, deleting, changing, or replacing their policies. iNexus is a tool for automated policy-based management of OpenWebServer. Its design is inspired by the natural immune system, particularly immune network, a truly autonomous decentralized system. iNexus inspects the current system condition of OpenWebServer periodically, measures the delivered quality of service, and selects suitable set of policies to reconfigure the system dynamically by relaxing constraints between them. The policy coordination process is performed through decentralized interactions among policies without a single point of control, as the natural immune system does. This paper discusses communication software can evolve continuously in the piecemeal way with biological concepts and mechanisms, adapting itself to ever-changing environment.

The optical structure of a conventional backlight illumination system used for transmissive LCD of a mobile terminal is investigated. A structured LGP based on the total internal reflection is designed and fabricated. The LGP is characterized by optical micro-deflectors (MD) and micro-reflectors (MR). The guided light inside the LGP is reflected on the MR elements and directed toward the MD elements. The coming light ray is refracted on the MD element and as a result the ray is deflected on the LGP. The emergent light on the LGP has a wide zenith angle due to the LGP surface normal. A prism sheet whose function is based on the total internal reflection is set on the LGP. The emanated light from the LGP is reflected on the surface of the prism structure and redirected toward the surface normal. The illumination cone of the novel backlight is limited to horizontal range of 17 degrees and vertical range of 11 degrees. The illumination cone on the novel structure can be shaped by optical designs of the MD and MR elements. The peak brightness on the novel backlight structure is 1.44 times that of the conventional one. In this backlight structure, only one TIR prism sheet is used and a thickness reduction of about 250 µm is achieved.

This paper proposes a precise method of realizing simultaneous measurement of microscopic defects and the macroscopic three-dimensional shapes of planar objects having specular reflection surfaces. The direction vector field of surface tilt is evaluated directly by the introduction of a moving slit-light technique based on computer graphic animation. A reflected image created by the moving slit-light is captured by a video camera, and the image sequence of the slit-light deformation is analyzed. The obtained direction vector field of the surface tilt recovers the surface shape by means of integration. Two sample objects, a concave mirror and a plane plastic injection molding, are tested to measure the performance of the proposed method. Surface anomalies such as surface dent and warpage are detected quantitatively at a high resolution (about 0.2 [µm]) and a high accuracy (about 95%) in a wide area (about 15 [cm]) of the test object.

Electric beam scanning reflector antennas provide beam scanning and pattern control, and can create narrow beams efficiently. However, they are not popular because the beam control circuit is large and difficult to realize. This paper proposes a new BFN configuration for cluster feeding of highly functional scanning antenna. The Enhanced PAttern Control nonswiTch (EPACT) BFN simplifies the beam control circuit and its control algorithm by using a fast Fourier transform (FFT) circuit, phase shifters, and a power divider. Furthermore, this paper proposes a design technique that uses modules to implement the FFT circuit and a method that optimizes amplifier placement to improve antenna efficiency. The design technique facilitates the manufacture of large-scale FFT circuits. The optimized amplifier location improves the antenna efficiency by eliminating the partial concentration of signal power.

Beam reconfiguration by structural reconfigurable antenna, such as the small multi-panel reconfigurable reflector antenna, has an aspect of great concern, that is the effects due to the use of a number of small panels to form the reflecting surface. It is thus a matter of great interest to numerically investigate all possible factors affecting the performance of this type of antenna such as: neighboring panels blocking, diffraction. The "null-field hypothesis" and PTD are employed to account for the effects of both phenomena on the main beam steering ability and the cross-polar level. In addition, the transformation of the polygonal flat domains into the square domains is applied in calculating the PO radiation field due to the various irregular polygonal flat sections of the arbitrary initial approximate reflector e.g., the flat circular reflector and the paraboloidal reflector. It is found that the main contribution to the total cross polarization is depolarization due to the finite size of the panels. The maximum cross-polar gain predicted using PTD is around -30 dB. The blocking effect has minor influence on cross-polarization. Both effects cause distortion on the co-polar pattern for the observer far from boresight but blocking has more influence than edge diffraction. Both effects have minor influence on the co-polar gain. The co-polar gain has variation of less than or equal to 0.07 dB in the flat case and 0.16 dB in the paraboloid case.

In this paper, we investigate the performance characteristics of parallel switching architectures constructed by a stack of multistage switching networks. We first find that the performances of the previously proposed parallel switching architectures are much worse than the expected ones from analytic models which are based on the assumption that traffic is uniformly distributed at each stage of a switching network. We show that this phenomenon is closely related to a traffic-distribution capability of a parallel switching system and has a large influence on the performance. From these results, we then propose an architectural solution based on the Generalized Shuffle Network (GSN) and analyze its performance by proposing a new iterative analysis method. The proposed architecture uses self-routing and deflection routing, and inherently has a traffic-distribution capability to improve switch performances such as cell loss and delay in a cost-effective manner. From the comparison of simulation and analysis results, it is shown that the developed models are quite accurate in predicting the performance of a new parallel switching system.

This paper describes the evaluation of a fiber-optic reflective displacement sensor that is compensated for variations in light source intensity, pressure, temperature and opacity of ambient medium. Additionally, the distance information is averaged over several points on the target surface, which reduces signal fluctuations due to inhomogeneities. Furthermore, a practical optical fiber reflective sensor model of measuring oil film thickness for thrust bearing is set up in this paper. Actual measurements were made with HEC 3000 tons' thrust bearing and the results were in good agreement with theoretical calculations.

We propose a compact multi-channel 90 optical deflection device for short-distance optical interconnection. The device consists of stacked bent multimode optical waveguides having reflecting mirrors with bending angles of 90. The structure of the bent multimode optical waveguide with a bending angle of 90 was designed by ray-tracing simulations. The simulated insertion loss for each channel of the device was 0.5 dB. We also propose a simple fabrication process using a pair of multi-channel linear optical waveguides with symmetrical 45 mirrors. An 8-channel 90 optical deflection device was fabricated using polymer materials and basic operation was confirmed. Our device has good potential for use as a high-density optical interconnection device.

We have discussed a ray tracing method to estimate the scattering characteristics from random rough surface. It has been shown from the traced rays that the diffracted rays dominate over the reflected rays. For the field evaluation, we have used the Fresnel function for the diffracted coefficient and the Fresnel's reflection coefficients. Numerical examples have been carried out for the scattering characteristics of an ocean wave-like rough surface and the delay spared characteristics of a building-like surface. In the present work we have demonstrated that the ray tracing method is effective to numerical analysis of a rough surface scattering.