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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 2, Issue 9, September 1966

Volumes & issues:

Volume 2, Issue 9

September 1966

Study of the propagation characteristics of a tropospheric radio link by the use of a laboratory model
New property of the stability diagram for curved-mirror resonators
  • Author(s): S.A. Harrison  and  W.K. Kahn
  • Source: Electronics Letters, Volume 2, Issue 9, p. 326 –327
  • DOI:  10.1049/el:19660275
  • Type: Article
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  • p. 326 –327 (2)
    Stable and unstable configurations for a curved-mirror optical resonator containing an inhomogeneous focusing medium have been computed on the basis of ray theory. These computations indicate the existence of six distinct regions on the stability chart of Boyd and Kogelnik. Most significantly, resonators initially within three of the regions become more stable, and those within the three remaining regions less stable, when perturbed by focusing effects due to a (convergent) inhomogeneous medium.
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Influence of charge effects on the electrical conductivity of thin metal films
Identification of a system in the presence of low-frequency drift
  • Author(s): W.D.T. Davies
  • Source: Electronics Letters, Volume 2, Issue 9, p. 327 –329
  • DOI:  10.1049/el:19660277
  • Type: Article
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  • p. 327 –329 (3)
    A technique is described, by which the elimination of error terms, due to low-frequency-drift disturbances, in the determination of the impulse-response function of a time-invariant system is achieved. The method uses a chain code as the perturbating input. It is shown that, by advancing the output rather than delaying the input, the errors that arise in the estimation of the impulse-response function are completely determined.
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Woven electron emitters for high reliability
  • Author(s): B.R.F. Kendall  and  H.M. Luther
  • Source: Electronics Letters, Volume 2, Issue 9, p. 329 –330
  • DOI:  10.1049/el:19660278
  • Type: Article
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  • p. 329 –330 (2)
    Results of tests carried out on woven and knitted electron emitters are summarised. The most outstanding characteristic of these emitters is their high reliability, which results from the multiplicity of current paths. Other features include good mechanical stability, transparency, a large effective emitting area and efficiency comparable with conventional filaments of the same materials.
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Transient changes in material conductivity due to impact ionisation in a Gunn-effect domain
  • Author(s): J.S. Heeks ; A.D. Woode ; C.P. Sandbank
  • Source: Electronics Letters, Volume 2, Issue 9, p. 330 –331
  • DOI:  10.1049/el:19660279
  • Type: Article
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  • p. 330 –331 (2)
    An interesting phenomenon is reported which occurs when a long sample of GaAs containing a high-field domain is subjected to an increased level of drive during part of it first cycle. Under such conditions there is produced locally, at the position where the domain is situated when the overdrive is applied, an increase in the free-carrier concentration, which then decays relatively slowly (approximately 1 μs). The effect is very similar to that first observed by Owens and Kino and ascribed by them to the generation of a second stable domain while the first is in transit through the device.
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Transfer-function matrixes
Nonlinear phase behaviour of travelling-wave tubes
Horowitz minimum-sensitivity decomposition
Analogue model for the signal-and-noise equivalent circuit of u.h.f. transistors
Elimination of the singularity in the power radiated by a point electric dipole in an unbounded magnetoplasma
Simultaneous estimation of first and second derivatives of a cost function
  • Author(s): D.W. Clarke  and  K.R. Godfrey
  • Source: Electronics Letters, Volume 2, Issue 9, p. 338 –339
  • DOI:  10.1049/el:19660285
  • Type: Article
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  • p. 338 –339 (2)
    A correlation method for estimating the second derivative, as well as the first derivative, of a cost function which is quadratic in an input parameter is described. The method, using a 3-level msequence perturbation signal, enables the cost-function minimum to be reached in a single step in a noisefree system. The effects of noise, and the extension of the method to multiparameter cost functions, are discussed.
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Walsh functions and Hadamard matrixes
Stability of negative-impedance convertors
Backscattering for circular polarisation
  • Author(s): M.W. Long
  • Source: Electronics Letters, Volume 2, Issue 9, p. 341 –342
  • DOI:  10.1049/el:19660288
  • Type: Article
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  • p. 341 –342 (2)
    Equations are given that express scattering for transmitting and receiving circularly polarised waves in terms of the characteristics for linear polarisation. Special cases are discussed, for which it is possible to estimate the radar cross-section for one polarisation based on data for other polarisations. Knowledge of polarisation characteristics is sometimes helpful for acquiring insight into the scattering mechanisms of complex surfaces.
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Asymptotic stability and the method of linear bounds
Very low-frequency measurements of flicker noise in silicon planar transistors
Direct calculation by analogue computer of sensitivity coefficients of linear and nonlinear systems
  • Author(s): Y. Sevely ; C. Durante ; F. Roubellat
  • Source: Electronics Letters, Volume 2, Issue 9, p. 345 –347
  • DOI:  10.1049/el:19660291
  • Type: Article
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  • p. 345 –347 (3)
    This letter gives a method which enables a direct analysis of sensitivity to parameter variations of linear or nonlinear systems to be simulated on an analogue computer. Based on the automatic changes ± Δq of a parameter q around a value q0, this method enables the dynamic sensitivity coefficient u(t, q0) to be computed with respect to this parameter by comparison of the disturbed solutions obtained in such a way.
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Stability of high-frequency transistor in common-emitter configuration
  • Author(s): C.L. Chao
  • Source: Electronics Letters, Volume 2, Issue 9, p. 347 –349
  • DOI:  10.1049/el:19660292
  • Type: Article
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  • p. 347 –349 (3)
    This letter describes the stability of the common-emitter transistor in terms of the y parameters in the high-frequency range; the graphical representation of the normalised input admittance of the transistor is also shown. This representation is useful and convenient for investigating performance of the input admittance in both design and analysis of circuits. The maximum frequency of potential instability of the common-emitter transistor is established using an approximate high-frequency equivalent circuit of a junction transistor.
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Sensitivity improvement of inductorless filters
Proposed method of measuring group-delay and amplitude characteristics over wide bandwidths
Maximally flat attenuation and delay characteristics
Constant-current source with unusually high internal resistance and good temperature stability
Coupled-wave equations for propagation in stratified compressible magnetoplasmas
Erratum: High-quality transistorised gyrator

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