摘要:

AbstractCellular systems are gaining wide acceptance. In Europe the GSM system is expected to provide service to more than 10 million users by the year 2000. Assuming that a demand for additional services at 64 kbit/s or so will not easily be satisfied either by the present GSM system or by advanced satellite systems at L‐band, this paper proposes a new satellite system at EHF (40150 GHz) to be integrated at the end of the decade with the GSM system or its descendants. First, the paper describes the main obstacles for the new system, in terms of channel characteristics and technology developments, and then illustrates a preliminary system design to show the technical feasibility in the proposed ten years time scal

ISSN:1124-318X    

DOI:10.1002/ett.4460010502

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

年代:1990

数据来源: WILEY

摘要:

AbstractDiffraction of a H,‐polarized plane wave by the discontinuties occurring in the material properties as well as in the thicknesses of a thin dielectric layer with a perfectly conducting backing is investigated. The effect of the dielectrics are simulated by second order generalized impedance boundary conditions which allow the structure to be treated as an infinitely thin two‐part plane.Then the solution is accomplished by the standard Wiener‐Hopf tech

ISSN:1124-318X    

DOI:10.1002/ett.4460010503

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe Archimedean printed spiral antenna is investigated by numerical methods, usjng the Green's function for stratified media.The integral equation for the current distribution is obtained by imposing the condition of vanishing total electric field tangential to the conducting strip and solved by application of the method of moments.Knowledge of the current on the arms of the antenna allows the evaluation of input impedance and radiation characteristics of the spiral.

ISSN:1124-318X    

DOI:10.1002/ett.4460010504

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper focusses on research and development activities for discrete components used either in high speed direct modulation or coherent systems, respectively. By taking full benefit of highly advanced epitaxial growth techniques like LPMOVPE and GSMBE new device structures have been realized.On the transmitter side a SIBH laser structure is reported which is especially designed for extremely low parasitics allowing for a transmission speed in excess of 10 Gbit/s. Results on DFB‐MQW lasers are presented. By making use of two dimensional effects these lasers have shown low threshold currents, high output power as well as narrow linewidth, which is of strong interest for both high bit rate and coherent transmission, Wavelength tunable lasers, such as multisection DFB or DBR lasers as well as a YCC‐I3laser, are investigated. With 3 section DFB‐lasers a linewidth of 3.5 MHz has been obtained. A 4‐channel FSK transmission experiment at 565 Mbit./s has been successfully performed. The passiv DBR lasers have shown a tuning range of 4.2 nm. With the novel YCC‐I3laser structure an enormous total tuning range of 22 nm together with a continuous tuning range of 1.15 nm with 20 dB sidemode suppression and a linewidth of 35 MHz has been achieved. Semiconductor travelling wave amplifiers are reported with high average internal gain of 28 dB at bias current of 50 mA. Using 4 cascaded amplifiers a 591 Mbit/s direct detection experiment of 279 km has been performed.Results on pin‐photodiodes and APD's are presented. Optimized pin‐detectors have been used to detect 20 Gbit/s pattern in a system experiment. Specially designed APD's are reported with a gain‐bandwidth pr

ISSN:1124-318X    

DOI:10.1002/ett.4460010505

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

年代:1990

数据来源: WILEY

摘要:

AbstractA method is proposed to calculate the capacitance of conducting MIS diodes based on a proper solution of the Poisson equation, which holds for any type of trap distribution in the oxide layer. This approach allows us to calculate the electric field and the voltage drop along the whole MIS structure, thus arriving at a general expression of its capacitance. By using these results, we obtain, as a special case, the usual expression for MIS diode capacitance in the presence of interfacial states. The theoretical l/Czvs reverse voltage characteristics of junctions with spatially distributed oxide traps present different slopes and voltage axis intercepts in comparison with those calculated by localizing interfacial states at the insulator/ semiconductor interface only.

ISSN:1124-318X    

DOI:10.1002/ett.4460010506

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

年代:1990

数据来源: WILEY

摘要:

AbstractParameters of optical fibres with zero dispersion at 1550 nm have been designed.In order to realize the critical core radius of 2.16 μm, some adjustments in pressurized MCVD process have been needed. A strict control of the process parameters during deposition, collapse and etching cycles allows to achieve the dispersion‐shifted fibre structure by MCVD as we

ISSN:1124-318X    

DOI:10.1002/ett.4460010507

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis work deals with the problems encountered in radiopaging systems employing the POCSAG code. In order to integrate the receiver's components, a Direct Conversion Receiver (DCR) should be used. When a simple demodulation procedure is employed problems due to the unacceptably high BER arise. The paper describes two solutions of the problem and gives experimental results showing how they reduce the BER in a common RF environment.

ISSN:1124-318X    

DOI:10.1002/ett.4460010508

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

年代:1990

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460010501

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

年代:1990

数据来源: WILEY