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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 15, Issue 4, 15 February 1979

Volumes & issues:

Volume 15, Issue 4

15 February 1979

Experimental study of surface-wave propagation on a low-permittivity medium
Large-bandwidth flat cylindrical array with circular polarisation and omnidirectional radiation
  • Author(s): G. Dubost ; J. Samson ; R. Frin
  • Source: Electronics Letters, Volume 15, Issue 4, p. 102 –103
  • DOI:  10.1049/el:19790074
  • Type: Article
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  • p. 102 –103 (2)
    Experimental properties of a flat cylindrical array with circular polarisation and omnidirectional radiation are presented. The thickness of the array wrapped on a perfect conducting cylinder is 0.04λ0. A bandwidth of 10% has been obtained. It is now possible to decrease the thickness by a factor 2 (i.e. to 0.02λ0), when using a short-circuited elementary source instead of a flat folded dipole, and yet retain the same band-width.
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Effect of reflector and exciter size on the radiation of circular-loop Yagi arrays
GaAs m.e.s.f.e.t. prepared by organometallic chemical vapour deposition
  • Author(s): H. Morkoç ; J. Andrews ; V. Aebi
  • Source: Electronics Letters, Volume 15, Issue 4, p. 105 –106
  • DOI:  10.1049/el:19790076
  • Type: Article
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  • p. 105 –106 (2)
    GaAs m.e.s.f.e.t.s with gate dimensions of 1.5 μm × 300 μm were fabricated in the epitaxial layers grown by organometallic chemical vapour deposition (o.m.c.v.d.) technique. The average saturation velocity in the channel was deduced to be 1.3 × 107 cm/s and is equal to that of epitaxial layers grown by AsCl3 chemical vapour deposition (c.v.d.). The velocity degraded region was confined to within about 350 Å of the interface. A gain of 10 dB and a noise figure of 3 dB with an associated gain of 5.5 dB at 8 GHz were measured.
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Ultimate low-loss single-mode fibre at 1.55 μm
Soft-decision decoding of the teletext character code
Gyrotropic waveguide switching elements at optical wavelengths
  • Author(s): P. Hlawiczka
  • Source: Electronics Letters, Volume 15, Issue 4, p. 109 –111
  • DOI:  10.1049/el:19790079
  • Type: Article
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  • p. 109 –111 (3)
    Principles of switching elements that use the variation of propagation properties of gyrotropic waveguides caused by changes in the orientation of the applied d.c. field are outlined. It is shown that packing densities comparable with magnetic-bubble devices (25 μm per cell) are readily obtainable and that applied magnetic fields and associated d.c. currents can be quite small, giving rise to minimal heat dissipation. Switching speeds in the nanosecond range are expected.
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Signal-level dependence in the recovery rate of irradiated plastic-clad silica fibre
Comment: Active simulation of inductors using current conveyor
Reply: Active simulation of inductors using current conveyor
Network condition for counter-clockwise reflection-coefficient behaviour: application to oscillators
Improvements on a cryogenically cooled mixer for 80–120 GHz
Error probability due to Gaussian noise and near-end crosstalk
Temperature dependence of impact ionisation rates in GaAs between 20° and 200°C
Pulse-widening measurement
Mapping of the near-field pattern in simulated biological tissues
  • Author(s): G. Gajda ; M.A. Stuchly ; S.S. Stuchly
  • Source: Electronics Letters, Volume 15, Issue 4, p. 120 –121
  • DOI:  10.1049/el:19790088
  • Type: Article
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  • p. 120 –121 (2)
    A simple system for mapping the electric-field pattern created in simulated biological tissue by a microwave applicator is described. The system employs a short probe sensitive to the E-field in one direction, which is driven along a sekcted path by the X-scan of an X-Y recorder while the intensity of the field measured by a diode detector is recorded simultaneously along the Y-coordinate of the recorder. Liquid dielectrics are used to simulate electric properties of the biological tissues. The system provides a viable complementary or alternative technique to the thermographic-camera method in evaluating the performance of microwave applicators for local hyperthermia.
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Bidirectional analogue optical transmission using semiconductor junction transceivers
Narrow-beam divergence of the emission from low-threshold GaInAsP/InP double-heterostructure lasers
  • Author(s): Yoshio Itaya ; Shinya Katayama ; Yasuharu Suematsu
  • Source: Electronics Letters, Volume 15, Issue 4, p. 123 –124
  • DOI:  10.1049/el:19790090
  • Type: Article
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  • p. 123 –124 (2)
    The angles of beam divergence perpendicular to the junction plane have been studied for low-threshold GaInAsP/InP double-heterostructure lasers with a thin active layer emitting at 1.31 μm. The narrowest beam divergence obtained was 23° for a laser diode with an active-layer thickness of 0.05 μm. At an active-layer thickness of 0.13 μm, the beam divergence was 40° with a threshold current density of 770 A/cm2.
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Design of f.i.r. direct-form digital filters with two quantisation steps
Electromagnetic power absorption in cylindrical tissue models excited by a loop antenna
Peak-amplitude detector for sinusoidal signals
Method for designing recursive digital filters with short wordlength
Broadband resonant filter using surface-shear-wave mode and twin-turn reflector
  • Author(s): Yasuaki Kinoshita ; Mitsutaka Hikita ; Toyoji Tabuchi ; Hiroomi Kojima
  • Source: Electronics Letters, Volume 15, Issue 4, p. 130 –131
  • DOI:  10.1049/el:19790095
  • Type: Article
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  • p. 130 –131 (2)
    A broadband resonant filter of a fractional bandwidth of up to 6% with an insertion loss under 3 dB has recently been developed using a surface shear wave mode on an LiNbO3Y-X substrate. The filter is realised on a substrate with thin metal electrodes, comprising a twin-turn reflector (two 3 dB multistrip couplers and four reflectors) and two interdigital transducers, without using additional matching inductors.
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Time moments and Markov parameters of composite systems
  • Author(s): Y. Shamash
  • Source: Electronics Letters, Volume 15, Issue 4, p. 131 –132
  • DOI:  10.1049/el:19790096
  • Type: Article
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  • p. 131 –132 (2)
    A theorem is given to show that a reduced-order composite system, formed from the interconnection of a number of reduced-order models that are Padé-type approximants of some subsystems, matches the initial time moments and Markov parameters of the composite system formed from the interconnection of these subsystems. Thus the reduced-order composite system has the same tracking properties as the original composite system.
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Twin-transverse-junction stripe laser with linear light/current characteristic and low threshold
  • Author(s): G.H.B. Thompson ; D.F. Lovelace ; S.E.H. Turley
  • Source: Electronics Letters, Volume 15, Issue 4, p. 133 –134
  • DOI:  10.1049/el:19790097
  • Type: Article
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  • p. 133 –134 (2)
    Lateral confinement of both light and carriers in the active region is achieved by creating twin transverse junctions with a deep Zn diffusion. The source is a stripe of SiO2 from which the Zn is diffused at low concentration into a highly n-doped double-heterostructure wafer. Threshold currents of around 30–40 mA have been measured and near and far fields of typically 3 μm and 10°, respectively, have been observed (both to half intensity). The optical control achieved results in linear light/current characteristics and zero-order-mode operation.
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Mesa-substrate buried-heterostructure GaInAsP/InP injection lasers
Quantising error in a Dolph-Cheby̅shev data-window multiplier circuit

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