Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 3, Issue 3, March 1967
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Volume 3, Issue 3
March 1967
General method of synthesis in the time domain of functions with discontinuities
- Author(s): G. Cartianu
- Source: Electronics Letters, Volume 3, Issue 3, p. 93 –94
- DOI: 10.1049/el:19670073
- Type: Article
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p.
93
–94
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A general method is described for the synthesis of time functions with a finite number of discontinuities of the function and of its derivatives in a given time interval. On the basis of the Laplace transform of the output, the functional scheme of the system is deduced. The synthesis can be affected by means of electrical analogue computers.
Effects of band-limiting the r.f. spectrum in a communication-satellite system employing wide-deviation frequency modulation
- Author(s): A.G. Reed
- Source: Electronics Letters, Volume 3, Issue 3, p. 95 –97
- DOI: 10.1049/el:19670074
- Type: Article
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p.
95
–97
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Reduction of the peak factor used in the design of frequency-modulation systems carrying multichannel telephony leads to a reduction of bandwidth, and therefore of thermal noise, at the expense of an increase in spectrum-truncation distortion. It is shown that the peak factor may be usefully reduced when the design carrier/noise ratio is high, but not when it is low, since such action raises the effective f.m. threshold.
Threshold region of f.d.m./f.m. signals
- Author(s): O. Shimbo
- Source: Electronics Letters, Volume 3, Issue 3, p. 97 –99
- DOI: 10.1049/el:19670075
- Type: Article
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p.
97
–99
(3)
Although many papers have been published concerning the analysis of the threshold region of f.m. signals, they are all incomplete. The present letter introduces a new analysis, in which the carrier is modulated by a Gaussian baseband signal, and gives important results which cannot be deduced from previous analyses.
Threshold improvement of f.m. systems by frequency-compression feedback
- Author(s): O. Shimbo
- Source: Electronics Letters, Volume 3, Issue 3, p. 99 –100
- DOI: 10.1049/el:19670076
- Type: Article
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p.
99
–100
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Two main causes are shown which prevent unlimited threshold improvement in frequency-compression-feedback systems when the feedback factor and modulation index both become large. It is shown that a previous explanation for this limitation is not correct, and also that an important term was neglected in the earlier analysis.
Glow-discharge tubes with monocrystalline cathodes
- Author(s): F.A. Benson and D.J. Mellor
- Source: Electronics Letters, Volume 3, Issue 3, p. 100 –101
- DOI: 10.1049/el:19670077
- Type: Article
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100
–101
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Some characteristics of glow-discharge reference tubes using single-crystal cathodes are given. The (100), (110) and (111) crystallographic planes were exposed to the glow. The (110) face was found to give excellent stability for the body-centred-cubic crystals used. Preferential cathodic etching was also observed.
Microwave lenses with nonlinear refractive index
- Author(s): P. Anastasovski and M. Ristov
- Source: Electronics Letters, Volume 3, Issue 3, p. 101 –102
- DOI: 10.1049/el:19670078
- Type: Article
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p.
101
–102
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Microwave lenses made from ferrite material change their optical characteristics when a d.c. magnetic field is acting. Experiments for changing the refractive index with lenses of D-type ferrite material and a wave frequency of 9GHz are described.
Two-stage selective RC amplifiers with small SQ sensitivities
- Author(s): M. Bialko
- Source: Electronics Letters, Volume 3, Issue 3, p. 102 –104
- DOI: 10.1049/el:19670079
- Type: Article
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p.
102
–104
(3)
The analysis and optimisation of two 2-stage selective amplifiers with complex RC feedback are given. These RC amplifiers have selective frequency characteristics similar to those of an amplifier with a single parallel LC resonance circuit, and have small SQ/x sensitivities. These facts enable their use in microelectronics and as low-frequency selective amplifiers with medium Qfactors.
Pulsed-r.f. slot-antenna breakdown controlled by preionisation and diffusion
- Author(s): M.H. Mentzoni and J. Donohoe
- Source: Electronics Letters, Volume 3, Issue 3, p. 104 –105
- DOI: 10.1049/el:19670080
- Type: Article
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p.
104
–105
(2)
The formative time lag for pulsed-r.f. breakdown is implicitly dependent on pulse-repetition rate and gas pressure because these parameters control preionisation level and diffusion losses. Experimental results in helium show that this dependence is in accordance with theoretical predictions.
Active gyrator
- Author(s): T. Yanagisawa and Y. Kawashima
- Source: Electronics Letters, Volume 3, Issue 3, p. 105 –107
- DOI: 10.1049/el:19670081
- Type: Article
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p.
105
–107
(3)
An active gyrator has both amplifying and impedance-inverting characteristics. A simple method of obtaining an active gyrator using two controlled-current sources is described. Such a circuit has inherent negative input and output resistances; so that ideal impedance-inverting char acteristics may be obtained. A simple experiment shows good agreement with theory.
Note on the sensitivity of a tunnel-diode-amplifier gain to variation of the negative-resistance value
- Author(s): G. Martinelli and A. Roveri
- Source: Electronics Letters, Volume 3, Issue 3, page: 107 –107
- DOI: 10.1049/el:19670082
- Type: Article
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p.
107
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A further contribution to the sensitivity of the gain to the variation of the negative-resistance value of a high-gain single-diode amplifier having a lowpass wideband characteristic is presented. It is proved that the use of a general passive embedding in place of a lossless one does not improve the sensitivity of these amplifiers.
Phase-locking of Gunn-effect oscillators
- Author(s): S.V. Judd and S.J. Hewitt
- Source: Electronics Letters, Volume 3, Issue 3, page: 107 –107
- DOI: 10.1049/el:19670083
- Type: Article
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p.
107
(1)
Phase-locking experiments of X band Gunn-effect oscillators are described. A locking gain of 38dB has been achieved for a frequency separation of 1MHz between the locking and driven oscillators.
Types of negative-immittance-convertor circuits
- Author(s): S.H. Manoli
- Source: Electronics Letters, Volume 3, Issue 3, p. 108 –109
- DOI: 10.1049/el:19670084
- Type: Article
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p.
108
–109
(2)
Steimel developed two vacuum-tube circuits from which he deduced the S- and N-type negative resistance, respectively. Many papers have subsequently been published in which special n.i.c. circuits are discussed. It is shown that these n.i.c. circuits are not different in principle, and can be deduced from one basic n.i.c. circuit.
Note on the relationship between the domain-transit frequency and the cavity-controlled frequency of thin Gunn devices
- Author(s): G.S. Hobson
- Source: Electronics Letters, Volume 3, Issue 3, p. 110 –111
- DOI: 10.1049/el:19670085
- Type: Article
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p.
110
–111
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Some measurements on thin Gunn devices mounted in cavities covering the range 7–20GHz are reported. For any particular device, it has been found that VBf is approximately constant, where VB is the bias voltage which gives maximum r.f. output at the frequency f. This observation has been related to the domain-transit frequency.
Variationally computed antenna impedances and accuracy of resulting current distributions
- Author(s): J. Galejs
- Source: Electronics Letters, Volume 3, Issue 3, p. 111 –114
- DOI: 10.1049/el:19670086
- Type: Article
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p.
111
–114
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The difference between a stationary and a nonstationary impedance formulation is shown to become zero if a complex current distribution produces zero tangential electric field along the metallic surface of the antenna. This difference between the two impedances is used as a criterion for establishing the accuracy for a given approximate current distribution. Illustrative examples consider dielectric-coated antennas in free space and insulated antennas in a magnetoionic medium.
Analysis of dynamic-characteristic curve of tunnel diodes
- Author(s): T. Koryu Ishii
- Source: Electronics Letters, Volume 3, Issue 3, p. 114 –115
- DOI: 10.1049/el:19670087
- Type: Article
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p.
114
–115
(2)
A “step” in the negative-resistance region of the voltage/current characteristic curve of an oscillating tunnel diode is theoretically analysed from the viewpoint of the conservation of energy. Tunnel diodes IN3219A and D4168D were experimentally investigated in the L and X bands. This step is attributed to the power conversion from d.c. to a.c.
Probability distribution of pseudorandom waveforms obtained from msequences
- Author(s): A.C. Davies
- Source: Electronics Letters, Volume 3, Issue 3, p. 115 –117
- DOI: 10.1049/el:19670088
- Type: Article
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p.
115
–117
(3)
The letter discusses the probability distribution of pseudorandom waveforms obtained from m sequences by summing the digits stored in the feedback shift register which generates the sequence. A recurrence relation is given, valid for both the binary and nonbinary cases, which enables the probability distribution to be determined easily.
On the derivative of the trace of a matrix quadratic form
- Author(s): P.W.U. Graefe and P.J. McLane
- Source: Electronics Letters, Volume 3, Issue 3, page: 117 –117
- DOI: 10.1049/el:19670089
- Type: Article
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117
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In the optimisation of linear systems with a random plant gain, the problem of computing the derivative of the trace of a matrix quadratic form is encountered. A derivation of this derivative is presented.
Hole and electron concentrations in a p-n-abrupt-junction diode as obtained by exact computer solution of the differential equations
- Author(s): M. Sánchez
- Source: Electronics Letters, Volume 3, Issue 3, p. 117 –119
- DOI: 10.1049/el:19670090
- Type: Article
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p.
117
–119
(3)
A computer solution for the current, continuity and Poisson's differential equations has been obtained for the forward steady-state behaviour of a 1-dimensional abrupt-p+-n-junction germanium diode at zero and at low to high injection levels at 300° K. The numerical integration has been performed inside and outside the space-charge layer of the p-n junction by using the Hall-Shockley-Read and the Auger recombination processes and by eliminating the Boltzmann equilibrium approximation in the space-charge layer and the space-charge neutrality approximation in the quasineutral p and nregion. The numerical results for the hole-and electron-concentration distributions are reported.
Comment: Scattering by infinite cylinders of arbitrary cross-section by the method of finite differences [and reply]
- Author(s): M.L. Burrows ; A.M. Patwari ; J.B. Davis
- Source: Electronics Letters, Volume 3, Issue 3, p. 119 –120
- DOI: 10.1049/el:19670091
- Type: Article
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p.
119
–120
(2)
A finite-difference method of computing the field scattered by conducting cylinders of arbitrary cross-section has recently been proposed by Patwari and Davies. The advantage claimed for their method—essentially that it overcomes the fundamental objection to the Rayleigh method—is shown to be unjustified and the two methods are, in fact, shown to be identical.
Photon-enhanced field emission from CdS single crystals
- Author(s): S. Akram Husain and D. Walsh
- Source: Electronics Letters, Volume 3, Issue 3, p. 121 –122
- DOI: 10.1049/el:19670092
- Type: Article
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121
–122
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In a previous experiment, field emission was observed from sharply pointed CdS single crystals. The experiments have now been extended, illuminating the tip with light from a pulsed argon-ion laser. It was found that (a) the voltage threshold at which emission can be observed is reduced, typically from 500 to 400 V, (b) under some conditions, the emission is increased by a factor of 103, (c) this emission persists for more than 2×10−2s after the laser pulse and appears to have two characteristic decay times, (d) the emission is approximately proportional to the light intensity and (e) the greatest photo-enhanced field emission was obtained with the laser light shining axially on the emitting area of the tip.
Computation of the Smith canonical form of a polynomial matrix
- Author(s): A.G. Dewey
- Source: Electronics Letters, Volume 3, Issue 3, page: 122 –122
- DOI: 10.1049/el:19670093
- Type: Article
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p.
122
(1)
An algorithm is given for the computation of the Smith canonical form of a polynomial matrix. A computer program employing this algorithm has worked successfully for fourth-order matrixes of high-degree polynomials.
Comments on the Lyapunov matrix equation [and reply]
- Author(s): S. Barnett ; C. Storey ; H.M. Power
- Source: Electronics Letters, Volume 3, Issue 3, p. 122 –123
- DOI: 10.1049/el:19670094
- Type: Article
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p.
122
–123
(2)
Parametric effects in an intrinsic 2-port magnetoelastic delay line
- Author(s): J.D. Adam ; I.M. Alexander ; J.H. Collins
- Source: Electronics Letters, Volume 3, Issue 3, p. 123 –124
- DOI: 10.1049/el:19670095
- Type: Article
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p.
123
–124
(2)
Experiments on parametric pumping of an L band 2-port magnetoelastic delay line are described. Two modes of operation were observed; namely, idler generation in an essentially 1-port régime and direct amplification of 2-port echoes.
Synthesis of Cheby̅chev digital filters
- Author(s): A.G. Constantinides
- Source: Electronics Letters, Volume 3, Issue 3, p. 124 –126
- DOI: 10.1049/el:19670096
- Type: Article
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p.
124
–126
(3)
A simple alternative approach to the conventional method for the synthesis of digital Cheby̅chev filters is outlined. Conventionally, digital filters are obtained by transforming Continuous filters. It is shown that synthesis of Cheby̅chev digital filters may be performed in the zplane, without referring to continuous filters.
Synthesis of the Hilbert transform of a train of rectangular pulses
- Author(s): D.J. Storey and R.F. Donne
- Source: Electronics Letters, Volume 3, Issue 3, p. 126 –128
- DOI: 10.1049/el:19670097
- Type: Article
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p.
126
–128
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A novel method of synthetising the Hillbert transform of a pulse train by nonlinear waveshaping circuits which avoids the use of complicated linear circuits is described.
Interpretation of the waveform of luminance-chrominance pulse signals
- Author(s): G. Rosman
- Source: Electronics Letters, Volume 3, Issue 3, page: 128 –128
- DOI: 10.1049/el:19670098
- Type: Article
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p.
128
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A direct solution is presented for the turning points of the signal envelope, the heights being simply related to the amplitude and delay distortion of the channel.
Field effect at 10 GHz
- Author(s): J.P. Flemming
- Source: Electronics Letters, Volume 3, Issue 3, p. 128 –129
- DOI: 10.1049/el:19670099
- Type: Article
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p.
128
–129
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An experimental method for the observation of field-induced conductance modulation at X band frequencies is described.
Optimisation of realisable receiver in pulse-amplitude modulation
- Author(s): P.D. Deighton
- Source: Electronics Letters, Volume 3, Issue 3, p. 129 –130
- DOI: 10.1049/el:19670100
- Type: Article
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p.
129
–130
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Using a criterion of minimum mean-square interference, the optimum linear and realisable receiver is specified for a noisy p.a.m. system. Constraining the optimum transfer function of the receiver to be given by a finite linear combination of orthonormal functions ensures its realisability in terms of RLCM elements.
Permittivities of single-crystal quartz at X band
- Author(s): J.G. Creer and G.J. Troup
- Source: Electronics Letters, Volume 3, Issue 3, page: 131 –131
- DOI: 10.1049/el:19670101
- Type: Article
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p.
131
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Although fused quartz (Si02) is known to have good dielectric properties at microwave frequencies, and, although Fe3+ in quartz is a possible maser material, the principal values of the permittivity for single-crystal quartz do not appear to have been determined in the microwave region. Preliminary measurements are presented of these at X band for high-quality, colourless mineral quartz, as used for piezoelectric crystals.
Erratum: Radiation from ring sources of electric or magnetic dipoles with different orientations in free space
- Source: Electronics Letters, Volume 3, Issue 3, page: 131 –131
- DOI: 10.1049/el:19670102
- Type: Article
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