Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887
banner image
image of Volume 26, Issue 4
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 26, Issue 4, 15 February 1990

Volumes & issues:

Volume 26, Issue 4

15 February 1990

MESFET fabrication on MOCVD grown Hg1-xCdxTe
  • Author(s): P.W. Leech ; P.J. Gwynn ; G.N. Pain ; N. Petkovic ; J. Thompson
  • Source: Electronics Letters, Volume 26, Issue 4, p. 221 –222
  • DOI:  10.1049/el:19900149
  • Type: Article
  • + Show details - Hide details
  • p. 221 –222 (2)
    The fabrication of the first MESFET structures on Hg1-xCdxTe is reported using MOCVD grown layers on GaAs substrates. The 6µm gate devices exhibited a room temperature transconductance of 1.0mS/mm and pinch off voltage of − 4.0V. The Schottky barrier characteristics of the devices were critically dependent on the stoichiometric x ratio of the Hg1-xCdxTe with diode formation evident only at x > 0.5.
    Add to favourites
    Export citations
Observation of self-lensing in a 4BCMU-polydiacetylene thin-film waveguide
Aperture coupled microstrip antenna element design
  • Author(s): R. Oostlander ; Y.M.M. Antar ; A. Ittipiboon ; M. Cuhaci
  • Source: Electronics Letters, Volume 26, Issue 4, p. 224 –225
  • DOI:  10.1049/el:19900151
  • Type: Article
  • + Show details - Hide details
  • p. 224 –225 (2)
    Aperture coupling is investigated as a feed mechanism for microstrip antenna elements. Using modal field expansion, and assuming that coupling is via a magnetic current in the aperture, calculated data on the antenna parameters are obtained. Several samples are manufactured, tested and practical design curves generated at 5.0 and 10 GHz. Good agreement between theory and experiment is obtained. These new results extend the validity of the analysis at high frequencies and will be useful for design and applications involving this type of antenna.
    Add to favourites
    Export citations
Effects of etch depth and ion implantation on surface emitting microlasers
  • Author(s): Y.H. Lee ; J.L. Jewell ; B. Tell ; K.F. Brown-Goebeler ; A. Scherer ; J.P. Harbison ; L.T. Florez
  • Source: Electronics Letters, Volume 26, Issue 4, p. 225 –227
  • DOI:  10.1049/el:19900152
  • Type: Article
  • + Show details - Hide details
  • p. 225 –227 (3)
    We fabricated low threshold In0.2Ga0.8As surface emitting microlasers having various etch depths and sizes. Comparison of electrical and optical properties was made between deep etched (deeper than the active layer) and shallow etched (shallower than the active layer) microlasers. Shallow etched microlasers were F-ion implanted to limit current spreading. The ion implanted shallow etched samples, when larger than about 5 µm across, show improved room temperature CW characteristics with lower resistances and lower operating voltages than the deep etched microlasers.
    Add to favourites
    Export citations
Conjugate gradient computation of the current distribution on a tripole FSS array element
Scan limitations of shaped dual-offset reflector antennas for multiple satellite access
  • Author(s): T.S. Bird  and  M.A. Sprey
  • Source: Electronics Letters, Volume 26, Issue 4, p. 228 –230
  • DOI:  10.1049/el:19900154
  • Type: Article
  • + Show details - Hide details
  • p. 228 –230 (3)
    The performance of offset Cassegrain antennas, shaped to provide wide scan angles, is outlined for use in earth stations which are capable of accessing several satellites simultaneously. The effect on the beam efficiency of scanning over a rectangular-shaped coverage region located about the geostationary arc is described. Limitations on scan performance are discussed as is the effect of satellite tracking by feed movement.
    Add to favourites
    Export citations
Identification and localisation of gate oxide weaknesses in n-MOS transistors through Fowler-Nordheim tunnelling and SPICE simulation
  • Author(s): D. Krakauer  and  B.S. Doyle
  • Source: Electronics Letters, Volume 26, Issue 4, p. 230 –231
  • DOI:  10.1049/el:19900155
  • Type: Article
  • + Show details - Hide details
  • p. 230 –231 (2)
    Analysis of the I/V characteristics after Fowler-Nordheim (F-N) injection of n-MOS transistors with weak source-drain overlap regions show the presence of an anomalous ‘hump’. SPICE simulations show that the same hump can arise in localised damage regions along the source-drain periphery, and that this is possibly in the bird's beak region. The results suggest that SPICE simulations and F-N injection can be used to study localised damage in MOS transistors.
    Add to favourites
    Export citations
Sidelobe suppression in an E-plane sectoral horn antenna
High-power single mode InGaAs/AlGaAs laser diodes at 910 nm
Comparison of three numerical treatments for the open-ended coaxial line sensor
  • Author(s): S. Jenkins ; A.W. Preece ; T.E. Hodgetts ; G.T. Symm ; A.G.P. Warham ; R.N. Clarke
  • Source: Electronics Letters, Volume 26, Issue 4, p. 234 –236
  • DOI:  10.1049/el:19900158
  • Type: Article
  • + Show details - Hide details
  • p. 234 –236 (3)
    The open-ended coaxial line sensor is commonly used for non-invasive microwave dielectric measurements. A comparison is made between three mathematical treatments that allow the reflection coefficient of the sensor to be derived from the complex permittivity of the material with which it is in contact. It is shown that the discrepancies between values computed by the three methods are much smaller than the predicted measurement uncertainties. Mappings of permittivity contours onto the complex reflection coefficient plane are shown.
    Add to favourites
    Export citations
High performance DFB-MQW lasers at 1.5 μm grown by GSMBE
Yield analysis of non-AR-coated DFB lasers with combined index and gain coupling
  • Author(s): K. David ; G. Morthier ; P. Vankwikelberge ; R. Baets
  • Source: Electronics Letters, Volume 26, Issue 4, p. 238 –239
  • DOI:  10.1049/el:19900160
  • Type: Article
  • + Show details - Hide details
  • p. 238 –239 (2)
    The threshold gain difference for DFB lasers with various degrees of gain coupling and different strengths of facet reflectivities is calculated as a function of the random phases between grating and facet reflectivities. From this, the yield for single mode behaviour is determined. It is shown that even for cleaved facets a relevant improvement in terms of threshold gain difference is obtained by introducing a small fraction of gain coupling.
    Add to favourites
    Export citations
Detectivity of gallium arsenide on silicon substrate photoconductive detectors
Optimisation of UHF antennas
Widely tunable Y-coupled cavity integrated interferometric injection laser
  • Author(s): M. Schilling ; H. Schweizer ; K. Dütting ; W. Idler ; E. Kühn ; A. Nowitzki ; K. Wünstel
  • Source: Electronics Letters, Volume 26, Issue 4, p. 243 –244
  • DOI:  10.1049/el:19900163
  • Type: Article
  • + Show details - Hide details
  • p. 243 –244 (2)
    A novel tunable single mode light source has been developed in the InGaAsP/InP material system. The Y-coupled cavity (YCC) type integrated interferometric injection (I3) wavelength tunable laser operates in the 1300nm wavelength region with a sidemode suppression of about 20dB. By adjusting the currents through the four all active sections of this YCC-I3-laser, a total tuning range of more than 14nm and continuous tuning of 1.15nm was obtained from nonoptimised first devices.
    Add to favourites
    Export citations
Performance evaluation of multilevel polarisation shift keying modulation schemes
  • Author(s): S. Benedetto  and  P. Poggiolini
  • Source: Electronics Letters, Volume 26, Issue 4, p. 244 –246
  • DOI:  10.1049/el:19900164
  • Type: Article
  • + Show details - Hide details
  • p. 244 –246 (3)
    The performance of coherent optical transmission systems using multilevel polarisation modulation is derived in terms of the symbol error probability. Four new multilevel modulation schemes based on equipower signal constellations at the vertices of regular polyhedra inscribed into the Poincaré sphere are proposed. For an increasing number of signals in the constellation, the shot noise performance of these systems show a remarkably less rapid degradation with respect to standard multilevel schemes with an equal number of signals.
    Add to favourites
    Export citations
Estimation of instantaneous frequency using the discrete Wigner distribution
  • Author(s): P. Rao  and  F.J. Taylor
  • Source: Electronics Letters, Volume 26, Issue 4, p. 246 –248
  • DOI:  10.1049/el:19900165
  • Type: Article
  • + Show details - Hide details
  • p. 246 –248 (3)
    Analytical expressions for the performance of the discrete Wigner distribution (DWD) in estimating the instantaneous frequency of linear frequency modulated signals in additive white noise are derived and verified using simulation. It is shown that the DWD peak provides an optimal estimate at high input signal-to-noise ratios. The applicability of these results to the general case of nonlinear FM signals is discussed.
    Add to favourites
    Export citations
Single sided switching networks
Real-time prediction of attenuation for applications to fade countermeasures in satellite communications
  • Author(s): L. Dossi
  • Source: Electronics Letters, Volume 26, Issue 4, p. 250 –251
  • DOI:  10.1049/el:19900167
  • Type: Article
  • + Show details - Hide details
  • p. 250 –251 (2)
    We have simulated the behaviour of a fade countermeasure control system that predicts the attenuation level on the satellite link on the basis of previous attenuation samples, using the experimental rain attenuation data measured at 11.6 GHz in three Italian stations with the Sirio satellite. Some dynamic characteristics of fading are investigated and the performances of prediction algorithms based on linear regression are evaluated.
    Add to favourites
    Export citations
Novel method for centre wavelength tuning of silica waveguide type Mach-Zehnder multi/demultiplexers
Parasitic insensitive single amplifier switched capacitor bandpass biquad
  • Author(s): C. Psychalinos  and  I. Haritantis
  • Source: Electronics Letters, Volume 26, Issue 4, p. 253 –254
  • DOI:  10.1049/el:19900169
  • Type: Article
  • + Show details - Hide details
  • p. 253 –254 (2)
    Switched capacitor biquads based on a loop consisting of two integrators generally require two operational amplifiers. In this letter, a bandpass biquad is proposed which is derived by following a different philosophy based on successive voltage inversions. This allows the use of a single operational amplifier and the realisation of a bilinear transformed continuous-time transfer function.
    Add to favourites
    Export citations
565 Mbit/s optical DPSK and PSK heterodyne transmission experiment using Nd:YAG lasers at 1.3 μm
Performance evaluation of polarisation shift keying modulation schemes
Two-dimensional modified Cauer form: circuit and state space realisation
Long wavelength infra-red photoconductive InAsSb detectors grown in Si wells by molecular beam epitaxy
Room temperature CW tunable green upconversion holmium fibre laser
Synthesis procedure for active integrated radiating elements
  • Author(s): V.F. Fusco  and  H.O. Burns
  • Source: Electronics Letters, Volume 26, Issue 4, p. 263 –264
  • DOI:  10.1049/el:19900175
  • Type: Article
  • + Show details - Hide details
  • p. 263 –264 (2)
    This letter demonstrates a technique for the synthesis of a new integrated active radiating element topology. The approach adopted uses a microwave MESFET operating in large signal mode as the active device in an oscillator configuration. The oscillator has as its parallel feedback element and load element a microstrip patch antenna. The synthesis approach developed in this paper uses numerical optimisation to find the optimum terminal voltages for a given MESFET at a specified frequency. A set of explicit equations are presented in terms of these optimum terminal voltages. These allow the active radiating element terminations to be realised analytically. An NE71000 chip is used as the active device in the active radiating element circuit. Construction is on RT Duriod 5880 and the circuit operated at 10.2 GHz with 30mW power delivered to the antenna.
    Add to favourites
    Export citations
New generation MMIC amplifier using InGaAs/InAlAs HEMTs
40 GHz measurement on InP/air gap line by picosecond electro-optic sampling
  • Author(s): S. Loualiche ; F. Clerot ; G. Audibert
  • Source: Electronics Letters, Volume 26, Issue 4, p. 266 –267
  • DOI:  10.1049/el:19900177
  • Type: Article
  • + Show details - Hide details
  • p. 266 –267 (2)
    An electro-optic sampling technique has been used to study an air gap microstrip line deposited on a semi-insulating InP substrate at frequencies up to 40 GHz. The 1 ps light pulses are obtained from a compressed mode locked Nd:YAG laser with a rubidium clock as a phase reference. The air gap line is compatible with III-V compound fabrication technology and can be used as an alternative to classical microstrip or coplanar plane wave interconnection techniques used in high speed devices. High frequency operation of this type of line does not require any thinning of the substrate and the effective dielectric constant is reduced by a factor of more than 3 compared with the dielectric constant of the substrate.
    Add to favourites
    Export citations
242 nm continuous tuning from a GRIN-SC-MQW-BH InGaAsP laser in an extended cavity
Series impedance simulators using one CCII
Uniform frequency modulation responses in narrow linewidth (≤ 200 kHz) compact hybrid lasers
  • Author(s): C.Y. Kuo ; E.J. Wagner ; D.A. Ackerman ; C.H. Henry ; Y. Shani ; M.I. Dahbura ; R. Kistler
  • Source: Electronics Letters, Volume 26, Issue 4, p. 270 –272
  • DOI:  10.1049/el:19900180
  • Type: Article
  • + Show details - Hide details
  • p. 270 –272 (3)
    Uniform frequency modulation (FM) response and narrow linewidth (≤ 200 kHz) are obtained simultaneously from a compact hybrid single frequency semiconductor laser. The hybrid laser consists of a two-electrode gain section, responsible for the uniform FM response, and a narrow band resonant optical reflector (ROR), responsible for the narrow linewidth. Uniform red shifted FM (DC to 200 MHz) is obtained when the section of lower injection current is modulated. The uniform FM response is attributable to inhomogeneous linewidth enhancement in the two laser sections created by nonuniform carrier injection.
    Add to favourites
    Export citations

Most viewed content for this Journal

Article
content/journals/el
Journal
5
Loading

Most cited content for this Journal

Print this page
This is a required field
Please enter a valid email address