Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 5, Issue 26, 27 December 1969
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Volume 5, Issue 26
27 December 1969
Analogue conductivity switch
- Author(s): T.L. Tansley and J.E. Ralph
- Source: Electronics Letters, Volume 5, Issue 26, page: 671 –671
- DOI: 10.1049/el:19690505
- Type: Article
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The current/voltage characteristics of Au-CaF2-n GaAs diodes have been found to exhibit a continuum of memory states, switchable with forward or reverse voltage pulses. The phenomenon is described and a possible charge-trapping mechanism indicated as being responsible.
Admittance of a phase-locked Gunn oscillator at high input powers
- Author(s): W. Frey
- Source: Electronics Letters, Volume 5, Issue 26, p. 672 –673
- DOI: 10.1049/el:19690506
- Type: Article
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A phase-locked Gunn oscillator can become passive at high input powers. The ‘reflection’ coefficient, defined by r=√(Pout/Pin), can drop to zero. Experiments on this behaviour are compared with a simple theoretical calculation.
Dispersive effects in microstrip on alumina substrates
- Author(s): S. Arnold
- Source: Electronics Letters, Volume 5, Issue 26, p. 673 –674
- DOI: 10.1049/el:19690507
- Type: Article
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The effect of dispersion on the phase velocity of microstrip transmission line on 99.5% alumina has been investigated by various methods. A comparison of these methods, together with a sample of the results obtained, is presented. The observed dispersion is discussed, and a simple empirical correction to the TEM approximation is outlined which accounts for this effect in 0.025 in-thick substrates.
Systems with generalised Riccati-Bernoulli nonlinearities
- Author(s): B.V. Dasarathy
- Source: Electronics Letters, Volume 5, Issue 26, p. 674 –675
- DOI: 10.1049/el:19690508
- Type: Article
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1st-order nonlinear systems described by a generalised form of Riccati-Bernoulli ordinary differential equations are shown to be reducible to equivalent linear systems of higher order through a nonlinear differential transformation. The method is generalised further to cover systems governed by partial differential equations with Riccati-Bernoulli-type nonlinearities.
Diffraction by an infinite dielectric cylinder due to a normally incident cylindrical wave
- Author(s): W.S. Hammond and M.A.K. Hamid
- Source: Electronics Letters, Volume 5, Issue 26, p. 675 –676
- DOI: 10.1049/el:19690509
- Type: Article
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The asymptotic value of the electric field diffracted by an infinitely long dielectric cylinder due to a normally incident cylindrical wave is computed by the geometrical theory of diffraction and shows excellent agreement with previous experimental results as well as the exact solution.
Iterative scheme for 1- and 2- dimensional d.c.-transistor simulation
- Author(s): J.W. Slotboom
- Source: Electronics Letters, Volume 5, Issue 26, p. 677 –678
- DOI: 10.1049/el:19690510
- Type: Article
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A numerical iterative scheme is presented for the solution of the 1- and 2-dimensional semiconductor d.c. transport equations. This scheme is applied to an n-p-n transistor structure. Input data are geometry, doping profile, boundary conditions and, optionally, mobility dependencies and generation-recombination law.
Simple technique for the accurate determination of delay-time variations in acoustic-surface-wave structures
- Author(s): J.D. Maines ; E.G.S. Paige ; A.F. Saunders ; A.S. Young
- Source: Electronics Letters, Volume 5, Issue 26, p. 678 –680
- DOI: 10.1049/el:19690511
- Type: Article
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A method of determining small variations in delay time of acoustic surface waves is described which is both simple and accurate. As an example, the technique is applied to determining the temperature vanation of delay time of surface waves propagating in the z direction on a y face of lithium niobate.
Simple criterion for the global regularity of vector-valued functions
- Author(s): M. Vehovec
- Source: Electronics Letters, Volume 5, Issue 26, p. 680 –681
- DOI: 10.1049/el:19690512
- Type: Article
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In the analysis of nonlinear networks it is usually necessary to perform functional inversion. The letter gives a compact and easily applicable criterion for the existence of a unique inverse of an important class of vector-valued functions, referred to as globally regular functions. The criterion is then used to establish global regularity of a few classes of functions in a very simple manner.
Positive network elements, a new class of elements possessing arbitrary hybrid description
- Author(s): M. Vehovec
- Source: Electronics Letters, Volume 5, Issue 26, p. 681 –683
- DOI: 10.1049/el:19690513
- Type: Article
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A new class of positive network elements is defined. It is a subclass of nonlinear resistive, capacitive and inductive (and possibly locally active) n-port [or (n+1)-terminal] elements. A positive network element possesses all possible hybrid descriptions. Also, all incremental driving-point resistances for a positive resistive element are themselves positive, as are capacitive and inductive elements. Many transistor and other active devices can be modelled as positive network elements.
Suboptimal control of plants with uncertain parameters
- Author(s): S.G. Rao and A.C. Soudack
- Source: Electronics Letters, Volume 5, Issue 26, p. 683 –684
- DOI: 10.1049/el:19690514
- Type: Article
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A two-level technique for optimal system design is proposed, in which trajectory sensitivity cost is included with state and control variable terms. The resulting optimal system would be less sensitive to plant-parameter variations than one designed without such a trajectory-sensitivity cost term.
Eigenvalues for higher-order conical-horn modes
- Author(s): P. Bhartia and M.A.K. Hamid
- Source: Electronics Letters, Volume 5, Issue 26, p. 684 –685
- DOI: 10.1049/el:19690515
- Type: Article
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Macdonald's formula, which is used to relate the associated Legendre and Bessel functions, is employed to find the approximate eigenvalues for TE and TM modes in a conical horn. Although the formula is restricted to small angles θ, it nevertheless provides a very simple and accurate method for calculating the eigenvalues of the fundamental and higher-order modes, even for large values of θ.
Propagation characteristics of inhomogeneous dielectric-filled coaxial cables
- Author(s): B. Chambers
- Source: Electronics Letters, Volume 5, Issue 26, p. 685 –686
- DOI: 10.1049/el:19690516
- Type: Article
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A general program has been written for calculating the attenuation and phase characteristics of the first TM surface-wave mode in an inhomogeneous dielectric-filled coaxial cable. As an example, the program has been used to study the special case of a coaxial cable with a very thin dielectric layer on the inner conductor.
B.C.D. serial adder/subtractor
- Author(s): J.D. Nicoud
- Source: Electronics Letters, Volume 5, Issue 26, p. 686 –687
- DOI: 10.1049/el:19690517
- Type: Article
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For the pure serial addition or subtraction of binary-coded decimal numbers, a simple network is proposed. It consists of a binary adder and a correction system using another adder. In an arithmetic unit, the position of this adder/subtractor at the beginning of the input/output register simplifies the design.
Enhanced photoemission into n hexane
- Author(s): A. Buttle and J.E. Brignell
- Source: Electronics Letters, Volume 5, Issue 26, p. 687 –688
- DOI: 10.1049/el:19690518
- Type: Article
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–688
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A gap between a photocathode and the liquid into which charge emission is directed considerably enhances the magnitude of photocurrent normally obtained. It also makes the process relatively insensitive to electronegative contaminants such as oxygen, even at stresses as low as a few tens of volts per centimetre.
Induced spiking in an ammonia-maser oscillator
- Author(s): W.S. Bardo and D.C. Lainé
- Source: Electronics Letters, Volume 5, Issue 26, p. 688 –689
- DOI: 10.1049/el:19690519
- Type: Article
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–689
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Oscillation pulsations (spiking) have been observed in the operation of an ammonia maser subjected to a periodic modulation of the oscillation condition.
Simulated inductance with a transistor and RC elements
- Author(s): P.S. Sarma and S. Venkateswaran
- Source: Electronics Letters, Volume 5, Issue 26, p. 689 –691
- DOI: 10.1049/el:19690520
- Type: Article
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–691
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An active RC circuit with a single transistor can realise a simulated inductance with even infinite Q factor. A design procedure is developed to realise a simulated inductance with infinite Q factor. Examples based on a particular transistor are included.
Influence of second-harmonic frequency termination on Gunn-oscillator performance
- Author(s): W. Frey ; H. Pollmann ; R.W.H. Engelmann ; B.G. Bosch
- Source: Electronics Letters, Volume 5, Issue 26, p. 691 –693
- DOI: 10.1049/el:19690521
- Type: Article
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–693
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Variations of the 2nd-harmonic frequency termination cause the output power of Gunn oscillators to change by a factor of up to five, accompanied by a frequency pulling of a few percent. From detailed impedance measurements it is concluded that the maximum fundamental power occurs if the 2nd-harmonic circuit is tuned near an open-circuit resonance, the total circuit susceptance apparently being somewhat capacitive.
Batch fabrication of integral-heat-sink IMPATT diodes
- Author(s): R.A. Zettler ; A.M. Cowley ; A.M. Engelmann
- Source: Electronics Letters, Volume 5, Issue 26, p. 693 –694
- DOI: 10.1049/el:19690522
- Type: Article
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A new technique for IMPATT-diode fabrication is described, in which the critical portion of the diode heat-flow path is formed as an integral part of the diode. The technique has economic advantages over conventional methods in that all processing steps are performed while diodes are still in wafer form. In addition, the technique permits passivation using standard dielectric deposition techniques, and the diode geometrical shape is such as to suppress premature edge breakdown. Typical experimental results are shown.
Example of the generalised-function validity of the Rayleigh hypothesis
- Author(s): M.L. Burrows
- Source: Electronics Letters, Volume 5, Issue 26, p. 694 –695
- DOI: 10.1049/el:19690523
- Type: Article
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–695
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The electromagnetic field scattered by a conducting circular cylinder is expressed as an outward-going wave expansion in an eccentrically placed polar-co-ordinate system. It is shown that the expansion is always valid on the cylinder surface in the generalised-function sense but not in the conventional-function sense.
Digital computation of frequency response of multiloop systems
- Author(s): J.R. Hewit
- Source: Electronics Letters, Volume 5, Issue 26, p. 696 –697
- DOI: 10.1049/el:19690524
- Type: Article
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–697
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An application-oriented program is described for the digital computation of the frequency response of linear multiloop systems. The main advantage of the program lies in the extreme simplicity of the data requirements and the consequent ease of application. Apart from the values of the parameters of the individual transfer functions comprising the overall system, the only other data required are a very simple and concise instruction array. The program has application in control-system design, compensation and stability analysis.
Variation of microstrip impedance with strip thickness
- Author(s): M.A.R. Gunston and J.R. Weale
- Source: Electronics Letters, Volume 5, Issue 26, p. 697 –698
- DOI: 10.1049/el:19690525
- Type: Article
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The letter indicates the way in which the characteristic impedance of single and coupled microstrip can vary with strip thickness, and points out that, in many cases of current practical interest, in both computer-circuit and microwave technologies, such variation is too large to be ignored without giving rise to serious error. Some typical graphs are given to illustrate this.
Linearly scaled power-factor meters employing solid-state switching circuits
- Author(s): H.G. Jänsch and I.R. Smith
- Source: Electronics Letters, Volume 5, Issue 26, p. 698 –700
- DOI: 10.1049/el:19690526
- Type: Article
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–700
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The letter describes two simple and novel linearly scaled power-factor meters. Solid-state devices are employed as switching elements and a precise indication of power factor is achieved over wide ranges of both current and voltage.
Stability of the damped Mathieu equation
- Author(s): A.J. Pritchard
- Source: Electronics Letters, Volume 5, Issue 26, p. 700 –701
- DOI: 10.1049/el:19690527
- Type: Article
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–701
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A method developed to generate Lyapunov functionals for distributed-parameter systems is applied to the damped Mathieu equation, the resulting Lyapunov functions giving rise to an improvement in the known stability boundaries.
General least-squares program for fitting functions to data
- Author(s): P.N. Murgatroyd
- Source: Electronics Letters, Volume 5, Issue 26, p. 701 –703
- DOI: 10.1049/el:19690528
- Type: Article
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A program is described which attempts to fit any function specified in a procedure, to a set of data. The values of a fixed number of disposable constants are systematically adjusted to minimise the sum of squares of differences between values and corresponding points of the function. An example is given of the use of the program in the analysis of an experimental autocorrelation function.
Contribution to the theory of phase-angle loci
- Author(s): H.M. Power
- Source: Electronics Letters, Volume 5, Issue 26, p. 703 –704
- DOI: 10.1049/el:19690529
- Type: Article
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Phase-angle loci for a rational function which has two zeros or two poles only are shown to be portions of rectangular hyperbolas. Simple rules are given for selecting appropriate portions from a prepared family of such curves. An application to root-locus plotting is described.
Anomalous propagation on v.h.f. radio links in the united kingdom
- Author(s): J.A. Lane and I.E. Owolabi
- Source: Electronics Letters, Volume 5, Issue 26, p. 704 –706
- DOI: 10.1049/el:19690530
- Type: Article
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An analysis of v.h.f. measurements made on 65 overland links up to 400 km in length has shown that the field strengths exceeded for about 1% of the time in band III (150–250 MHz) are greater than previously predicted. The enhancement of band III signals relative to band I (41–68 MHz) on an adjacent, similar path sometimes reaches 40 dB when a layer of large gradient in refractive index is situated at a height of about 0.5–0.6 km
New engineering approach to the calculation of losses in coaxial cables
- Author(s): H.M. Barlow
- Source: Electronics Letters, Volume 5, Issue 26, p. 706 –708
- DOI: 10.1049/el:19690531
- Type: Article
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The attenuation of a coaxial cable has been calculated using a more precise method, applicable to the case of a homogeneous dielectric between bare metal surfaces. It appears that the actual loss is 17% higher than is predicted by conventional TEM theory.
Comment on ‘Improved method of solution of 2-point boundary-value problems arising in optimal control’ [and reply]
- Author(s): P.L. Neely and A. Griffin
- Source: Electronics Letters, Volume 5, Issue 26, p. 708 –709
- DOI: 10.1049/el:19690532
- Type: Article
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In a recent letter, Griffin describes a method for solving the 2-point boundary-value problem arising in optimal control. The proposed method is only valid in certain special cases, and this is discussed in the present communication.
Proposed high-efficiency spherical-reflector antenna
- Author(s): P.J.B. Clarricoats and S.H. Lim
- Source: Electronics Letters, Volume 5, Issue 26, p. 709 –711
- DOI: 10.1049/el:19690533
- Type: Article
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A technique is proposed for raising the efficiency of sphereical-reflector antennas embodying the Gregorian method of phase correction. The method is based on the Galindo-Williams modified Cassegrain antenna. An additional subreflector is introduced between the Gregorian corrector and the spherical reflector, in order to cause the power rom the feed horn to be uniformly distributed over the main reflector aperture. Equations are presented which enable the co-ordinates of the subreflectors to be computed. Two examples are given and a theoretical effieciency of 93% is predicted in one case.
N-path filter sections with biquadratic transfer functions
- Author(s): W. Saraga
- Source: Electronics Letters, Volume 5, Issue 26, p. 711 –714
- DOI: 10.1049/el:19690534
- Type: Article
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Explicit design formulas are given for elementary N-path sections, with biquadratic transfer functions Tr(p), which consist of first-order RC path networks and multiplier-type modulators actuated by sinusoidal carrier oscillations [higher-degree transfer functions being realisable by cascading elementary sections]. By varying the phase angle between input and output carriers, the transmission zeros of Tr(p), and therefore its character, can be varied over wide ranges.
Vapour growth of multilayered GaAs structures for series operation of transferred-electron oscillators
- Author(s): R.E. Enstrom ; J.F. Reynolds ; B.E. Berson
- Source: Electronics Letters, Volume 5, Issue 26, p. 714 –715
- DOI: 10.1049/el:19690535
- Type: Article
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Series operation of GaAs transferred-electron oscillators has been obtained by the in situ vapour growth of n+−n−n+−n−n+ structures. Devices fabricated from this structure have operated at n/f ratios as high as 3.2 × 105 s cm−3 and have yielded conversion efficiencies as high as 13.5% at 4.0 GHz.
RC:RL decomposition of a fourth-order polynomial
- Author(s): D.P. Leach and S.P. Chan
- Source: Electronics Letters, Volume 5, Issue 26, p. 716 –717
- DOI: 10.1049/el:19690536
- Type: Article
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p.
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A set of three conditions which are necessary and sufficient for the RC: RL decomposition of a 4th-order polynomial is derived. The conditions are expressed in terms of the Qs and the coefficients of each quadratic factor, and the method thus offers a computational advantage over a previous method.
Novel approach to synthesis of multivariable positive real functions
- Author(s): N.K. Bose and A.M. Soliman
- Source: Electronics Letters, Volume 5, Issue 26, p. 717 –718
- DOI: 10.1049/el:19690537
- Type: Article
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The possibility of synthesis of multivariable positive real functions, bilinear in one variable, using a simple configuration is demonstrated. The result is illustrated by two examples.
Discrepancies in waveguide-attenuation expressions
- Author(s): M.M. Brady and A.S. Norconsult
- Source: Electronics Letters, Volume 5, Issue 26, p. 718 –719
- DOI: 10.1049/el:19690538
- Type: Article
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Waveguide-attenuation expressions given in the literature disagree by as much as 0.2%, which exceeds the precision customarily associated with waveguide computations. In addition, the UK DEF standard waveguide-attenuation expression is shown to be misleading. A rectangular waveguide is specifically treated and standard waveguide-attenuation expressions are suggested.
Coupled-mode description of beam-plasma interaction
- Author(s): Ho. Bong
- Source: Electronics Letters, Volume 5, Issue 26, p. 719 –720
- DOI: 10.1049/el:19690539
- Type: Article
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A coupled-mode method is used to analyse the interaction between the slow space-charge wave of an electron beam and the electroacoustic wave of a lossless warm plasma. A transmission-line analogue of the plasma electroacoustic wave is developed. Maximum gain expression is obtained from the solution of the beam-plasma coupled-mode equations.
Phase filter, an untested f.m. demodulator
- Author(s): D.R. Hummels
- Source: Electronics Letters, Volume 5, Issue 26, p. 720 –722
- DOI: 10.1049/el:19690540
- Type: Article
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A new demodulator structure, the phase filter, is proposed for f.m.-threshold extension. A mathematical model is derived which shows the structure is equivalent to a conventional phase-lock loop preceded by a linear filter operating on the phase of the received signal.
Erratum: Propagation characteristics of magnetoelastic surface wave
- Author(s): J.P. Parekh
- Source: Electronics Letters, Volume 5, Issue 26, page: 722 –722
- DOI: 10.1049/el:19690541
- Type: Article
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