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1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 14, Issue 4, 16 February 1978
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Volume 14, Issue 4
16 February 1978
Use of current controlled GaAs l.p.e. for optimum doping profiles in l.s.a. diodes
- Author(s): D.J. Lawrence and L.F. Eastman
- Source: Electronics Letters, Volume 14, Issue 4, p. 77 –78
- DOI: 10.1049/el:19780052
- Type: Article
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p.
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–78
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Microwave device quality GaAs, grown by the electric current-controlled liquid-phase epitaxy method, is reported. Ratios of peak current to valley current near the theoretical limit for the corresponding layer doping and thickness are reported, along with high breakdown voltages in unloaded l.s.a. oscillators.
The influence of a fibre structure on optical loss in a graded-index fibre
- Author(s): Norio Kashima ; Naoya Uchida ; Nobuhiko Susa ; Shigeyuki Seikai
- Source: Electronics Letters, Volume 14, Issue 4, p. 78 –80
- DOI: 10.1049/el:19780053
- Type: Article
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p.
78
–80
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For designing a fibre structure, the influence of structural parameters on optical loss is investigated experimentally for a graded-index fibre. The fibre with large cladding/outer-layer index difference and small cladding thickness is found to have large excess loss near excitation points, such as a launching point and a splicing point.
Low temperature electroplated Au–SnNi–Au ohmic contacts on n type GaAs
- Author(s): William M. Kelly and Gerard T. Wrixon
- Source: Electronics Letters, Volume 14, Issue 4, p. 80 –81
- DOI: 10.1049/el:19780054
- Type: Article
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p.
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–81
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A method is described for fabricating ohmic contacts on n type GaAs by alloying electroplated layers of Au-SnNi-Au at 300°C, resulting in a contact resistance of approximately 3 × 10−5 Ω cm2. In applications for which this resistance is adequate, the technique has the advantage of requiring low-temperature alloying for short times.
Quasi-optical channel diplexer using Fabry–Perot resonator
- Author(s): Ryuichi Watanabe and Nobuo Nakajima
- Source: Electronics Letters, Volume 14, Issue 4, p. 81 –82
- DOI: 10.1049/el:19780055
- Type: Article
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p.
81
–82
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A new type of quasi-optical diplexer is presented. It consists of one polarisation splitter, two quarter-wave plates, and two plane-parallel Fabry-Perot resonators working under normal incidence. Measured dropped- and through-channel losses at 100 GHz frequency range were about 1 dB and 0.5 dB respectively.
Binary baseband polar signals in combination with continuous and impulsive noise with i.s.i.
- Author(s): V.K. Jain and S.N. Gupta
- Source: Electronics Letters, Volume 14, Issue 4, p. 82 –83
- DOI: 10.1049/el:19780056
- Type: Article
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p.
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–83
(2)
This letter presents the performance of a binary baseband polar system in the presence of a mixture of continuous and impulsive noise and intersymbol interference (i.s.i.). The results obtained are very general and the system performance in special cases like purely continuous noise or purely impulsive noise with or without i.s.i. can be easily derived from the general results.
Demonstration of a c.c.d. image processor for two-dimensional edge detection
- Author(s): G.R. Nudd and P.A. Nygaard
- Source: Electronics Letters, Volume 14, Issue 4, p. 83 –85
- DOI: 10.1049/el:19780057
- Type: Article
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p.
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–85
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An analog technique for image processing that provides 2-dimensional edge detection is described. The algorithm implemented is the Sobel operator using a 3 × 3 array of picture elements. The implementation is unique in that a fully integrated circuit approach is employed which has the potential of being integrated directly into either an optical or infrared sensor. The n channel charge-coupled device (c.c.d.) technology used results in a processor area of less than 0.06 cm2, and can provide an increase in processing speeds of several orders of magnitude over general-purpose machines. Typical results from this processor are given and are compared with computer simulation.
Pulsed laser annealing of zinc implanted GaAs
- Author(s): S.S. Kular ; B.J. Sealy ; K.G. Stephens ; D.R. Chick ; Q.V. Davis ; J. Edwards
- Source: Electronics Letters, Volume 14, Issue 4, p. 85 –87
- DOI: 10.1049/el:19780058
- Type: Article
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–87
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Samples of n type GaAs implanted with 1015Zn+/cm2 at room temperature were irradiated with a ruby laser of pulse length 0.8 ms. For samples coated with Si3N4 a laser energy of 1.5–2.5 J/cm2 produced electrical activity of 40–50% of the implanted dose. Peak hole concentrations up to about 7 × 1019 cm−3 were measured. Uncoated samples irradiated with similar laser energies were not electrically active.
A new d.h. laser configuration with passive transverse field confinement
- Author(s): T.E. Rozzi ; J.H.C. van Heuven ; G.H. In'T Veld
- Source: Electronics Letters, Volume 14, Issue 4, p. 87 –88
- DOI: 10.1049/el:19780059
- Type: Article
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p.
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–88
(2)
A new geometry is proposed which significantly improves the characteristics of single mode d.h. stripe geometry lasers, with regard to astigmatism of the near field, transverse field confinement, modal gain and threshold current. The advantages over other devices are discussed. Numerical results are presented for 5 and 10 μm stripe lasers.
Improved chemical vapour deposition method for long-length optical fibre
- Author(s): M. Okada ; M. Kawachi ; A. Kawana
- Source: Electronics Letters, Volume 14, Issue 4, p. 89 –90
- DOI: 10.1049/el:19780060
- Type: Article
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p.
89
–90
(2)
The deformation of the supporting tube during the c.v.d. process for optical fibre fabrication is completely suppressed by controlling the internal pressure of the tube. A 14 km length single-mode fibre with attenuation loss of about 3.2 dB/km at 0.85 μm was fabricated by this improved method.
Effect of wall thickness on radiation from circular waveguides
- Author(s): G.L. James and K.J. Greene
- Source: Electronics Letters, Volume 14, Issue 4, p. 90 –91
- DOI: 10.1049/el:19780061
- Type: Article
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p.
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–91
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An experimental study shows that the thickness of a circular waveguide wall greatly affects its radiation characteristics. The exact solution of Weinstein for infinitely thin walls appears in practice to be valid only when the wall thickness is less than 0.01 λ.
20ps/Gate Gunn-effect high-speed carry finding device
- Author(s): Nobuo Hashizume ; Shoei Kataoka ; Kazutaka Tomizawa
- Source: Electronics Letters, Volume 14, Issue 4, p. 91 –92
- DOI: 10.1049/el:19780062
- Type: Article
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p.
91
–92
(2)
Improvement was made on our recently reported Gunn-effect high-speed carry finding device, which can now perform logic operations with a minimum delay time of 20 ps/gate. The improvement is concerned with the means of nullifying the effect of the nonuniformity of the constituent m.e.s.f.e.t.s.
A minterm interchange operation in the Walsh spectrum domain
- Author(s): E. Eris
- Source: Electronics Letters, Volume 14, Issue 4, p. 92 –94
- DOI: 10.1049/el:19780063
- Type: Article
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p.
92
–94
(3)
A mathematical operation is investigated in the Walsh spectrum domain which corresponds to the interchange of any minterms of a Boolean function.
Effect of rain in the near field of an antenna
- Author(s): D.P. Haworth ; N.J. McEwan ; P.A. Watson
- Source: Electronics Letters, Volume 14, Issue 4, p. 94 –96
- DOI: 10.1049/el:19780064
- Type: Article
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p.
94
–96
(3)
The effect of rain on the field at a point irradiated by a microwave antenna is found, in contrast with previous work, to be effectively independent of the parameters of the antenna. The standard Fresnel zone criterion for the ‘active rain volume’ has been extended to treat rain in the near field of the antenna.
Application of super-resolution techniques to time domain reflectometry systems
- Author(s): B. Chambers
- Source: Electronics Letters, Volume 14, Issue 4, p. 97 –98
- DOI: 10.1049/el:19780065
- Type: Article
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p.
97
–98
(2)
By application of the principles of super timing (i.e. sharpening of the time resolution for a given bandwidth) it is shown that the resolution of a t.d.r. system can be improved beyond the classical limit imposed by the rise time of the step generator. The discussion is supported by experimental results.
Prediction of dual-shaped-reflector antenna crosspolarisation
- Author(s): T.S. Bird
- Source: Electronics Letters, Volume 14, Issue 4, p. 98 –100
- DOI: 10.1049/el:19780066
- Type: Article
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p.
98
–100
(3)
An efficient computer program for the analysis of dual-shaped-reflector antennas is described. This is used to predict the crosspolarisation of a typical earth station antenna. Employing a feed with intrinsic crosspolarisation, it is shown that the crosspolar performance of the antenna may be reflector depolarisation limited. The effect of subreflector beam steering on the crosspolar response is also discussed.
Investigation into the survival of epitaxial bipolar transistors in current mode second breakdown
- Author(s): M. Dow and K.I. Nuttall
- Source: Electronics Letters, Volume 14, Issue 4, p. 100 –101
- DOI: 10.1049/el:19780067
- Type: Article
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p.
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–101
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Measurements have been obtained of the time for which epitaxial transistors are able to survive when pulsed into the current mode second breakdown condition. The results have been analysed to provide information on the nature of the constricted current distribution. The work indicates the effects that emitter geometry has on the extent of the current constriction.
Groove guide propagation characteristics at 3mm wavelength
- Author(s): D.J. Harris and K.W. Lee
- Source: Electronics Letters, Volume 14, Issue 4, p. 101 –102
- DOI: 10.1049/el:19780068
- Type: Article
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p.
101
–102
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Measurements of moding characteristics and attenuation on groove guide with appropriate dimensions for 3 mm wavelength operation show that it can be made with convenient dimensions, can operate with only the single dominant mode, and have a loss less than 1 dB/m.
Switching conduction in ion-irradiated layers in GaAs
- Author(s): A.J.N. Houghton
- Source: Electronics Letters, Volume 14, Issue 4, p. 102 –103
- DOI: 10.1049/el:19780069
- Type: Article
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p.
102
–103
(2)
Experiments have been performed to investigate whether switching phenomena are observable in ion-irradiated GaAs. It is found that the V/I characteristics of H2+-and N+-irradiated layers show both negative resistance and switching from a high resistance to a low resistance state. Ion irradiation may thus be a useful method of fabricating switching devices.
Discrete radiation from curved single-mode fibres: a comparison of theories
- Author(s): R.A. Sammut
- Source: Electronics Letters, Volume 14, Issue 4, p. 103 –104
- DOI: 10.1049/el:19780070
- Type: Article
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p.
103
–104
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An apparent discrepancy between coupled-mode and ‘whispering-gallery’ theories for the radiation of discrete beams from curved single-mode fibres is resolved. It is shown that the two formally different approaches are in very good agreement with each other in predicting the periodicity of the radiation.
Optimum decoding of M-ary polarisation modulated laser signal
- Author(s): Nilamber Malaviya
- Source: Electronics Letters, Volume 14, Issue 4, p. 104 –105
- DOI: 10.1049/el:19780071
- Type: Article
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p.
104
–105
(2)
A decision rule has been derived for optimum decoding of an M-ary polarisation modulated signal in a laser communication system.
Relative phase measurements at 30 GHz between copolar and induced crosspolar signals produced by ice particles on a satellite-to-ground link
- Author(s): P.F. Shutie ; E.C. Mackenzie ; J.E. Allnutt
- Source: Electronics Letters, Volume 14, Issue 4, p. 105 –107
- DOI: 10.1049/el:19780072
- Type: Article
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p.
105
–107
(3)
Observations of relative phase variations between the copolar and crosspolar signals, produced by ice particles, on a 30 GHz satellite-to-ground link are presented. A mechanism, involving differential phase shift between orthogonal components of a linearly polarised wave, is discussed.
Computer display of vowel quadrilateral with real-time representation of articulation
- Author(s): G.J. Bristow and F. Fallside
- Source: Electronics Letters, Volume 14, Issue 4, p. 107 –109
- DOI: 10.1049/el:19780073
- Type: Article
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p.
107
–109
(3)
The classical characterisation of vowel sounds used by phoneticians is the vowel quadrilateral, which originally was assumed to be the locus of the tongue body between its four extreme vowel positions. A method of real-time computer analysis and display which represents the vowel quadrilateral is described. This has application in computer-based speech training aids, but may have wider use in speech research generally.
Adaptive instantaneous pitch detector with microcomputer error correction
- Author(s): N.R. Malik and S.C. Huang
- Source: Electronics Letters, Volume 14, Issue 4, p. 109 –110
- DOI: 10.1049/el:19780074
- Type: Article
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p.
109
–110
(2)
A microcomputer is interfaced with an analogue circuit to detect the pitch of voiced speech over a 50 to 500 Hz range in real time.
Crossovers in microstrip
- Author(s): R. Horton
- Source: Electronics Letters, Volume 14, Issue 4, p. 110 –111
- DOI: 10.1049/el:19780075
- Type: Article
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p.
110
–111
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The fabrication and characterisation of a crossover structure in microstrip is described. The results indicate the means to achieve either high isolation between physically intersecting signal paths, or a controlled amount of coupling for applications where this is desirable.
Optimum single-zero lead compensation of systems having two dominant poles
- Author(s): G.J. Sloggett
- Source: Electronics Letters, Volume 14, Issue 4, p. 111 –113
- DOI: 10.1049/el:19780076
- Type: Article
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p.
111
–113
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For multipole feedback systems having two dominant poles, simple approximations are given for the zero which is optimum in the sense that gain margin is maximised, and for the corresponding maximum marginal gain. The formulas permit rapid design of optimum single-zero lead compensation for such systems.
Measurement of single-mode fibre core-cladding concentricity
- Author(s): A.R. Tynes ; R.M. Derosier ; W.G. French
- Source: Electronics Letters, Volume 14, Issue 4, p. 113 –115
- DOI: 10.1049/el:19780077
- Type: Article
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p.
113
–115
(3)
Single-mode fibre core-cladding concentricity has been measured by using a fibre splicing technique. In this technique a short length of fibre is broken in two and one length is rotated about its own axis α degrees with respect to the other length and then the two lengths are spliced together. The splice loss when α = 180° is a direct measure of the fibre butt-joint offset and hence also of the concentricity of the core and the cladding. A submicrometre sensitivity for this measurement has been achieved.
On exact compensation of transfer inefficiency in a charge-transfer delay line
- Author(s): S.C. Dutta Roy and V.G. Das
- Source: Electronics Letters, Volume 14, Issue 4, p. 115 –116
- DOI: 10.1049/el:19780078
- Type: Article
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115
–116
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Expressions are derived for the feedback coefficients required to compensate, exactly, for the transfer inefficiency in a charge-transfer device delay line with nonidentical, lossy stages. A tuning algorithm is also given for adjustment of these feedback coefficients.
Improved mean power and long pulse width operation of InP t.e.o.s in J band
- Author(s): L.D. Irving ; J.E. Pattison ; P.W. Braddock ; K.W. Gray
- Source: Electronics Letters, Volume 14, Issue 4, p. 116 –117
- DOI: 10.1049/el:19780079
- Type: Article
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116
–117
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Two zone cathode InP t.e.o.s. with plated heat sinks are reported that give peak powers up to 21 W, mean powers up to 1.5 W, and are capable of operation at pulse widths of 50 μs.
On a sequential regression predictor
- Author(s): D. Soldan and N. Ahmed
- Source: Electronics Letters, Volume 14, Issue 4, p. 118 –119
- DOI: 10.1049/el:19780080
- Type: Article
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p.
118
–119
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This communication is concerned with the notion of adaptive prediction via sequential regression. The related predictor involves a finite impulse response (f.i.r.) digital filter, and is implemented using a sequential regression (s.e.r.) algorithm which was published recently. Experimental results are presented, and for the purposes of comparison, corresponding results obtained via the Widrow algorithm2 are also included.
An asynchronous logic array for the realisation of logic systems with concurrency
- Author(s): M. Courvoisier
- Source: Electronics Letters, Volume 14, Issue 4, p. 119 –121
- DOI: 10.1049/el:19780081
- Type: Article
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p.
119
–121
(3)
An array circuit able to implement any logic system described by a Petri net is presented. It uses a request acknowledge asynchronous functioning mode and constitutes a simplification of a solution proposed by Patil previously.
Radiation conductance of open-circuit low dielectric constant microstrip
- Author(s): C. Wood ; P.S. Hall ; J.R. James
- Source: Electronics Letters, Volume 14, Issue 4, p. 121 –123
- DOI: 10.1049/el:19780082
- Type: Article
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p.
121
–123
(3)
The existing discrepancies between formulas for the radiation conductance of an open-circuit microstrip line are investigated and comparison made with measurements of improved accuracy. It is found that consistent results are obtained if an allowance is made for field-fringing effects in those analyses based on radiation from apertures.
A membrane wave delay line
- Author(s): Mauri Luukkala and Pekka Meriläinen
- Source: Electronics Letters, Volume 14, Issue 4, p. 123 –124
- DOI: 10.1049/el:19780083
- Type: Article
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p.
123
–124
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Membrane waves are excited in thin, stretched polycarbonate foils. Waves up to hundreds of kilohertz are easily excited with single strip electrostatic excitation. The waves are trapped in the film, exhibit a low loss and their propagation velocity can be varied by changing the applied tension.
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