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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 13, Issue 16, 4 August 1977

Volumes & issues:

Volume 13, Issue 16

4 August 1977

Microwave modulation by amorphous-semiconductor switches
  • Author(s): D.N. Bose  and  B.J. Jani
  • Source: Electronics Letters, Volume 13, Issue 16, p. 451 –452
  • DOI:  10.1049/el:19770325
  • Type: Article
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  • p. 451 –452 (2)
    Microwave modulation has been achieved by using thin-film amorphous-semiconductor switches made of ternary chalcogenides. X-band microwaves were modulated by a threshold switch at frequencies varying from 100 Hz to 1 MHz, with modulation efficiencies comparable to siliconp–i–n diodes. The insertion loss was 0.5 to 0.6 dB and the isolation was 18 dB at 100 mA operating current. Possible applications this method are discussed.
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Optical transmission experiment at 1.12 Gbit/s using a graded-index fibre with a length of 1.652 km
  • Author(s): C. Baack ; G. Elze ; G. Walf ; G. Gliemeroth ; D. Krause ; N. Neuroth
  • Source: Electronics Letters, Volume 13, Issue 16, p. 452 –453
  • DOI:  10.1049/el:19770326
  • Type: Article
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  • p. 452 –453 (2)
    The letter describes the transmission of an optical p.c.m. signal with a pulse rate of 1.12 Gbit/s by using a graded-index fibre with a length of 1.652 km and a c.w. semiconductor laser as transmitter. We studied the dependence of the dispersion on the laser wavelength and on the coupling arrangement between laser and fibre. For estimating the material dispersion, we analysed the dynamic spectral behaviour of the laser.
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Fast numerical algorithm for the recompression of dispersed time signals
  • Author(s): A.K. Booer ; J. Chambers ; I.M. Mason
  • Source: Electronics Letters, Volume 13, Issue 16, p. 453 –455
  • DOI:  10.1049/el:19770327
  • Type: Article
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  • p. 453 –455 (3)
    A fast numerical algorithm is presented for recompressing signals propagated over different path lengths in a dispersive duct. It is shown that an appropriate distortion of a signal spectrum recompresses dispersed arrivals regardless of their arrival times. The method is applied to the preprocessing of seismic data acquired in an underground pulse-echo location system for imaging faults in coal seams.
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Slant-path attenuation through rainstorms
Novel c.c.d. signal integrator
Efficient hard-wired digital fast-Fourier-transform processor
Deep-level changes associated with the degradation of GaAs0.6 P0.4 l.e.d.s
  • Author(s): C. López ; A. García ; E. Muñoz
  • Source: Electronics Letters, Volume 13, Issue 16, p. 460 –461
  • DOI:  10.1049/el:19770331
  • Type: Article
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  • p. 460 –461 (2)
    The generation of deep levels in GaAS0.6 P0.4 electroluminescent diodes during forward-bias degradation has been studied by transient capacitance techniques. By comparison with the native trapping centres, it is concluded that only hole trap concentration increases during aging. This result is correlated through current/voltage, light/current, reverse-recovery-time and infrared-radiation measurements.
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Coloration and its reduction in phosphorus-doped low-loss optical fibres
Transmission of radio signals in deep-level gold mines indirectly via power cables
Necessary criteria for the diagnosis of panel misalignments in large reflector antennas by microwave metrology
Equivalent circuit of coaxial-to-microstrip connector over the 8–12 GHz range
  • Author(s): S.O. Ajose  and  N.A. Mathews
  • Source: Electronics Letters, Volume 13, Issue 16, p. 465 –466
  • DOI:  10.1049/el:19770335
  • Type: Article
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  • p. 465 –466 (2)
    An equivalent circuit of OSM–244–4 ASF coaxial-to-microstrip connector is presented. The dielectric-filled coaxial line region of the connector is represented by a 50 ω air line and the coaxial-to-microstrip transition by a T-network. An optimisation procedure is employed to obtain optimum component values of the equivalent circuit from the measured input reflection coefficient into the connector fixed on an open-circuited microstrip line.
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Adaptively designed test logic for digital circuits
Instantaneous change in current gain produced by burst noise in a planar transistor
Low-frequency multiplication noise in reference diodes for small multiplication factors
Input correlation with the a.s.w. storage correlator
Coaxial-cable equaliser employing active distributed RC networks
Schottky mixer diodes made by a new method
Synthesis of some partially symmetric Boolean functions by ternary algebra
Regenerative transistor power switch
Model for charge propagation in a resistive-gate m.o.s. structure
Stabilising circuit for a tuned-circuit magnetic levitator
Effect of surface distortions on the crosspolarisation performance of paraboloidal reflectors
  • Author(s): B. MACA. Thomas  and  P.T. Rayner
  • Source: Electronics Letters, Volume 13, Issue 16, p. 478 –480
  • DOI:  10.1049/el:19770346
  • Type: Article
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  • p. 478 –480 (3)
    The effects on the crosspolarisation and the radiation patterns of circular paraboloidal reflectors produced by (a) reflector distortions which are periodic in the circumferential direction and (b) a lateral offset of the feed have been evaluated for a wide range of reflector and feed parameters. It is shown that the use of a balanced hybrid-mode feed minimises crosspolarisation introduced by reflector distortions.
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Nonlinear theory of long-range-interaction resonant generators
  • Author(s): A.A. Shmat'Ko ; O.A. Tretiykov ; D.M. Vavriv
  • Source: Electronics Letters, Volume 13, Issue 16, p. 480 –481
  • DOI:  10.1049/el:19770347
  • Type: Article
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  • p. 480 –481 (2)
    A nonlinear self-consistent theory has been developed for resonant electronic generators of long-range interaction. The theory has been under development for devices whose electrodynamic system has a high Q-factor and a sufficiently rarefied spectrum. In accordance with the initial physical situation, the mathematical model under consideration has been obtained in the form of a system of differential equations, and an algorithm for its numerical solution has been proposed. The maximum amplitude of the generated oscillations in an open cavity with a Gaussian distribution of the field has been calculated analytically.
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Wideband equalisation and signal averaging applied to the pulse echo return loss testing of telecommunication coaxial cables
  • Author(s): P. Cochrane  and  J.K. Perkins
  • Source: Electronics Letters, Volume 13, Issue 16, p. 481 –482
  • DOI:  10.1049/el:19770348
  • Type: Article
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  • p. 481 –482 (2)
    A pulse echo return loss testing technique is described that has been developed as a maintenance aid for high-bit-rate digital transmission systems. Wideband equalisation and signal averaging have been used to achieve the high positional resolution coupled with the high sensitivity necessary to allow echo sources to be detected at any point in a regenerator section. A brief description of the equipment is given together with an example of the results achieved under laboratory conditions.
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Radiation-induced degradation of ohmic contacts
Small-area, high-radiance c.w. InGaAsP l.e.d.s emitting at 1.2 to 1.3 μm
  • Author(s): A.G. Dentai ; T.P. Lee ; C.A. Burrus ; E. Buehler
  • Source: Electronics Letters, Volume 13, Issue 16, p. 484 –485
  • DOI:  10.1049/el:19770350
  • Type: Article
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  • p. 484 –485 (2)
    Double-heterostructure InP/lnGaAsP/lnP high-radiance l.e.d.s have been fabricated by liquid-phase epitaxy on the <IIIB> face of commercially available InP substrates. The best small-area l.e.d.s had a useful external power efficiency of 1.5% and a 900 Å-wide emission spectrum centred at 1.23 μm. emitting ∼3 mW into the air at 100 mA and 2 V; essentially similar results were obtained with devices operating al 1.30 μm.
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Synthesis of cutpoint cellular arrays with exclusive-OR collector row
Submicrometre Al0.5Ga0.5As heterojunction gate GaAs f.e.t.
  • Author(s): H. Morkoc ; S.G. Bandy ; G.A. Antypas ; R. Sankaran
  • Source: Electronics Letters, Volume 13, Issue 16, p. 487 –488
  • DOI:  10.1049/el:19770352
  • Type: Article
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  • p. 487 –488 (2)
    Preliminary results on the d. c. and microwave performance of Al0.5Ga0.5 As gate heterojunction GaAs field-effect transistors (h.j.f.e.t.) with submicrometre gate lengths are reported. The structure is of a 3-layer sandwich formed by an n-type 1017 cm3 Sn-doped active layer on a Cr-doped substrate, a p-type 1015 cm−3 Ge-doped Al0.5Ga0.5As gate layer and a p+-type 5 × 1013 cm-3 Ge-doped GaAs ‘cap' layer on the top of the gate. Selective etching of the p+ GaAs and p-Al0.5Ga0.5As provides the necessary overhang for self-aligned device fabrication. Experimental devices with sub-micrometre gate lengths and with a gate periphery of 300 μm have exhibited a d. c. transconductance of 20 to 30 mS and an m.a.g. of 9.5 dB at 8 GHz. To our knowledge, this is the first time a submicrometre gate h.j.f.e.t. has been fabricated to give amplification of power at X-band.
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Correlation parameters of random binary sequences
Phase of crosspolarised signals on microwave satellite links
  • Author(s): N.J. McEwan
  • Source: Electronics Letters, Volume 13, Issue 16, p. 489 –491
  • DOI:  10.1049/el:19770354
  • Type: Article
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  • p. 489 –491 (3)
    For a linearly polarised satellite link in the 4–30 GHz range, ‘anomalously high’ crosspolar signals caused by differential phase shift should always exhibit a phase of nearly ±90 relative to the wanted polarisation. This principle might permit an adaptive cancellation system using only one variable parameter (amplitude); it does not necessarily apply for circular polarisation, a possible advantage of linear over circular polarisation on practical links.
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Erratum: Diffraction-optimised shaped-beam reflector antennas
Erratum: Analogue c.c.d. correlator using monolithic m.o.s.t. multipliers
Erratum: Matrix formulation of corrugated feeds by using impedance boundary conditions
Erratum: Estimating the correlation coefficient of highly correlated clutter
Erratum: Unified active structure for an arbitrary 2-port network realisation
Comment on ‘Design of stable 2-dimensional discrete recursive filters’ [and reply]

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