Published papers

The diffusion-induced strain and dislocation effects on the diffusion of phosphorus into silicon have been investigated. When phosphorus is diffused singly, the diffusion coefficient of phosphorus increases considerably at high concentrations. While, when phosphorus and germanium are diffusion simultaneously, fewer dislocations areobserved and the　diffusion-induced strain is compensated. In strain-compensated diffusion, concentration profiles of phosphorus agree well with the theoretical curves (erfc). It is shown that the enhancement of the diffusion　coefficient of phosphorus at high concentrations is attributed to the diffusion-induced strain. Besides, dislocations retard the diffusion front by absorbing excess vacancies, showing the opposite effect of strain.

The prototype atmospheric optical communication system has been developed, and various field tests have been carried out in Tokyo andNiigata. The system with a laser diode can transmit a 4-MHz color television signal or 120 telephone channels. This paper gives an outline description of system design based on field test results.

The radio-relay system for simultaneous transmission of telephone and video signals has been developed to transmit 4 MHz color videosignal and　multiplexed telephone signals simultaneously via existing FDM microwave　transmission systems to which some equipments are added. The addedequipment are the circuit-connecting equipment which combines with and　separates into the multiplexed telephone signals and color video signal,　and the system switching equipment. This system has been used as the transmission system of a video conference system which started operation　from May 1976, and the satisfactory result is obtained. The system is　expected to play an importantrole as the video transmission system of the　video conference system, because it can be realized economically and　briefly by carrying out a few changes on the existing microwave　transmission system in the 5 GHz SF-E1 system, the 6 GHz SF-U3 system, the　11 GHz SF-T5 system and others.

Describes construction and performance of a 400 Mb/s 4-phase　shiftkeying repeater operating in the 20 GHz band. The repeater consistsof all solid-state devices such as transistors and IC's. Gunn diodes are used　for a transmitter local oscillator, and IMPATT diodes for a receiver local oscillator. A PIN diode is adopted as a switching diode for a 20 GHz band　direct phase-modulator. The 4-phase coherent detection circuit design method is developed with an intermediate frequency of 1.7 GHz. Expected　overall repeater error rate characteristics were satisfied, and an　extremely stable repeater was realized with less than 4 dB of equivalent　C/N degradation over the -10 degrees C to 45 degrees C temperature range.

The repeater is totally solid state for miniaturisation, high reliability and economy with the adoption of microwave IC's, monolithicIC's, and direct oscillation by Gunn diodes in the 20-GHz band. Themodulation and demodulation techniques of the repeater employ　QPSK,which has a theoretical advantage over FSK, DPSK, or ASK in error　rate performance, considering spectrum utilisation. The error rate performance is further improved by using a simple digital equalisation for　intersymbol interference. The error rate performance of thissystem was　measured. From the test results, it became evident that the equivalent carrier-to-noise ratio (C/N) degradation of error rate performance at a　10/sup -6/ error rate was about 5 dB under fixed temperature conditions　and that the equivalent C/N degradation due to a -10 degrees C to +45　degrees C temperature variation was only 1 dB.

Operation of a band reflection type cavity stabilized Gunn oscillator　is analyzed by considering its dynamic characteristics. The properties of　convenient for measurement and its coupling with a band reflection type　frequency stabilizing circuit is discussed. Reduction of the output power as a result of frequency stabilization is studied and it is found that the　power dissipated by a matched load is small. FM noise is measured and Rieke diagrams are constructed,thus providing a frame of reference for the　design theory of this type of Gunn oscillator.

A repeater capable of transmitting a 400 Mb/s digital signal in the 20 GHz band is described. The repeater is equipped with transistors and IC　for receiver mixer, IF amplifier, demodulator, and carrier recovery　circuit. Gunn diodes are used for transmitter and receiver local　oscillator and transmission power amplifier. For effectiveuse of the radio　frequency, q.p.s.k. is adopted as multi-level modulation, and coherent　detection as demodulation. The required transmission band can be limited by compensating for the intersymbol interference. Overall error rate　characteristics of the experimental repeater almost attain the predetermined goal, and an extremely stable repeater is realized with an　error rate degradation of 1 dB underambient temperature variations between　-10 degrees and +45 degrees C.

The transmitter consists mainly of a 20 GHz band direct 4 PSK　modulator including a pulse shaper and a pulse amplifier, a band reflection type transmitting local oscillator using a 20 GHz Gunn diode　and an injection locked amplifier. It also has an alarm signal detection　circuit, FM modulator for sending supervision and control signal, and DC current stabilized power supply sources. Output power is19.0 dBm or more, when the temperature variation is from -10 degrees to +45 degrees C, maximum modulation phase error is 5 degrees or less, transmitting frequency variation is within +or-3 MHz and output power variation is +1.0　approximately -1.5dB.

The Electrical Communication Laboratory has completed the　construction of the 20-GHz digital radio repeater. This paper discusses　itserror rate performance. The discussion centres on various causes　oferror rate degradation. The theoretical results derived using approximated equations are verified by the experiment. Overall performance of the experimental repeater is evaluated and the effectiveness of the　method of evaluating the performance is confirmed.

A new type of highly frequency stabilized self-oscillating up-convertor using transferred-electron diodes is described. Experiments　were made under the following conditions. Self-oscillating frequency(local　frequency), signal frequency (IF), and output frequency were20.1 GHz, 1.5 GHz and 18.6 GHz, respectively. The best result achieved was a maximum　power output of +14 dBm, a 3-dB bandwidth of 1 GHz, and a self-oscillating frequency stability of 1.2*10/sup -6// degrees C.

A new type of frequency-stabilization method, for a Gunn oscillator consisting of a high-Q single-tuned oscillator circuit is described. The frequency stability of this stabilized oscillator was 5*10/sup 5/ over a temperature change from -10 to 60 degrees at 20.970 GHz. This result satisfies the requirement for a 20-GHz radio relay system.

A new type of solid-state microwave transmitter which consists of a low noise Gunn modulator and a high power IMPATT amplifier is described. The transmitter satisfies the requirements for a short haul baseband relay The transmitter satisfies the requirements for a short haul baseband relay equivalent.

The key words for future telecommunications are personalization, multimedia services and high accessibility to the network. These trends naturally lead to radio media application to access links. In this sense, this paper proposes an advanced wireless access system with a capacity supporting broadband video and data services. The concept of the system can be defined as a new radiocommunication category with advantages of both fixed and mobile systems. The system is designed to transport ATM-based signals using SHF (or EHF) bands to wireless terminals, interconnected with optical fibers at the network side. The basic system configuration is presented as well asexamples of system parameters. For radio aspects the maximum service coverages of the radio base stations are calculated based on availability considerations. Preferred frequency bands for actual operation are also discussed.

将来の通信の方向として，パーソナル化，マルチメディア化および高アクセシビリティ化が今後ますます重要となり，無線によるアクセスシステムの構築が不可欠と なると思われる。本論文では，将来のパーソナル通信への適用を目指し，ワイヤレスアクセスノード，ワイヤレスアクセスポイントおよびマルチメディア携帯情報端 末から構成されるアドバンストワイヤレスアクセスシステムを提案し，そのシステムコンセプト，システム構成，技術課題等について述べる。ワイヤレスアクセスノ ードとワイヤレスアクセスポイントの間は，広帯域伝送および高品質特性を確保するために光ファイバにより接続され，その中を無線周波数帯の信号が「ファイバ無 線」技術により伝送される。本アドバンストワイヤレスアクセスシステムは，音声サービスだけでなく画像やデータ通信を含むマルチメディアワイヤレスアクセスサービスを提供できる。

パーソナルハンディホンシステム（ＰＨＳ）は，ディジタルコードレス技術をベースとした最先端の無線アクセス系技術と，インテリジェントなディジタルネットワークを統合化した新しい通信サービスであり，通信のパーソナル化とマルチメディア化を実現する第１歩として位置付けられる。このＰＨＳサービスの早期提供を目 指して，ＮＴＴはその研究開発を強力に進めるとともに標準化に寄与してきた。本論文では，ＰＨＳの構想，無線系およびネットワークインタフェースの研究開発な らびに我が国における標準化の経緯を総括する。

A novel masterslice MMIC is presented that expands the possibilities for three-dimensional (or multilayer) MMIC technology. This MMICincorporates two levels of ground metals, resulting in an effectiveselection of master-array elements on the wafer surface by using the lower-level metal and a circuit-stacking effect by the upper one.X-band amplifier and receiver MMIC's on 3*1 and 6*3 array-units, respectively, are also demonstrated in very small areas.

日本における無線呼び出しの加入者数は７００万を超え，コードレス電話は年間３００万台以上販売されており，全部で１０００万台以上が稼働中で，セルラの加入者数も１５００万を超えた。パーソナルコミュニケーションの代表である，セルラ，一般公衆電話，ＩＳＤＮ回線の三つの領域が融合したパーソナルハンディーホン（ＰＨＳ）の構成，屋外電話市場への影響，需要見込み，将来の公衆陸上移動通信であるＦＰＬＭＴＳとの関係等について紹介した。

本論文は，筆者の２６年間の研究生活を基に無線通信全般に対して技術的見解を述 べたものである。はじめに無線通信の歩んだ道と題して，研究所が開発してきた無線通信システムの歴史を振り返るとともに，各システムが果たした歴史的役割に対する考えを述べる。次に，無線システムの分析と題して，これまで，独立に研究開 発を進めてきた固定・移動体・衛星の各無線通信システムを同じテーブルにのせて議論する。最後に，無線通信システムの目指す道と題してこれからの方向を考える。