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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 8, Issue 14, 13 July 1972

Volumes & issues:

Volume 8, Issue 14

13 July 1972

Pyroelectric properties of lead germanate
  • Author(s): G.R. Jones ; N. Shaw ; A.W. Vere
  • Source: Electronics Letters, Volume 8, Issue 14, p. 345 –346
  • DOI:  10.1049/el:19720252
  • Type: Article
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  • p. 345 –346 (2)
    An evaluation of the pyroelectric properties of ferroelectric lead germanate Pb5Ge3O11 in both single-crystal and ceramic form is presented. It is shown that the expected noise-equivalent power for lead germanate is similar to that of triglycine sulphate, and the voltage responsivity is slightly lower. The superior chemical and mechanical properties of lead germanate make it an attractive alternative for use in pyroelectric detectors.
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Identification of linear systems using correlation data
Theory of optimum M-ary laser detection
  • Author(s): A.K. Kamal ; P.D. Sharma ; N. Malaviya
  • Source: Electronics Letters, Volume 8, Issue 14, p. 348 –349
  • DOI:  10.1049/el:19720254
  • Type: Article
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  • p. 348 –349 (2)
    An upper bound on the average error probability of all possible M-ary optical systems, using large-average photon statistics, has been derived. This bound clearly indicates the superiority of the M-ary system over the binary one in terms of allowable transmission rates below which the error rate decreases exponentially with code-block length. A probabilistic solution for the problem of efficient signal selection has been found and demonstrated with a simple illustration.
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Frequency/temperature characteristics of Gunn devices
  • Author(s): R. Davies ; W.S.C. Gurney ; A. Mircea
  • Source: Electronics Letters, Volume 8, Issue 14, p. 349 –351
  • DOI:  10.1049/el:19720255
  • Type: Article
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  • p. 349 –351 (3)
    The variability and large magnitude of the frequency/temperature coefficient of Gunn oscillators has limited the application of these devices. The letter outlines a program of experiments and computer simulations aimed at achieving an understanding of the basic ∂f/∂T mechanism and thus producing a deep stable oscillator. Our simulations successfully predict observed trends in the ∂f/∂T behaviour of Gunn devices with both alloyed metal and n+ regrown contacts. The results of our study show that stable oscillators with a small loaded Q factor and near maximum power output are realisable.
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Improved geometry for a semiconductor surface-wave oscillator
Image-cancelling mixers
  • Author(s): D.P. Howson  and  J.G. Gardiner
  • Source: Electronics Letters, Volume 8, Issue 14, p. 352 –354
  • DOI:  10.1049/el:19720257
  • Type: Article
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  • p. 352 –354 (3)
    Image-cancelling mixers are a form of image-recovery or image-enhancement mixer. The method of operation is discussed and the possible circuit arrangements are derived. It is shown that it is necessary to have a π/2 phase shift in the local oscillator path to one mixer, and a corresponding phase shift in the i.f. path of the same mixer. No restrictions appear necessary on the phase shifts in the signal paths, but it is argued that equal-signal phase shifts to the two mixers are advantageous.
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Stability circle criterion with 3rd-order spatial-harmonic balance for nonlinear distributed-parameter systems
Differential d.c. conductance of a p-n-junction space-charge region
Multimillisecond timse delays with wrap-around surface-acoustic-wave delay lines
Frequency-modulation sensitivity and frequency-pushing factor of a pd-n-p+ punchthrough microwave diode
Design of nonrecursive digital moving-target-indicator radar filters
Transition from sheath-convection to saturation-current behaviour of a Langmuir probe in a flowing plasma
  • Author(s): R.M. Clements ; R.D. Kerr ; A.A. Offenberger ; P.R. Smy
  • Source: Electronics Letters, Volume 8, Issue 14, p. 361 –362
  • DOI:  10.1049/el:19720263
  • Type: Article
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  • p. 361 –362 (2)
    The transition between diffusive (saturated-current) and sheath-convection [current ∝(voltage)½] behaviour of the current to a negatively biased Langmuir probe in a plasma jet has been studied experimentally by varying the electron density over a wide range. The measurements verify for the first time the expected change in the dependence of current on voltage. However, this change occurs at higher electron densities than expected, and, when saturated-current behaviour is finally obtained, these currents are significantly lower than their calculated values and, surprisingly, remain close to the sheath-convection currents calculated for moderate voltages.
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Reciprocal but nonsymmetrical transmission characteristics of tapered irises
Electron-relaxation effects in transferred-electron devices revealed by new simulation method
Optimum loading for relaxation l.s.a. diode
  • Author(s): M. Wasse ; J. Mun ; J.S. Heeks
  • Source: Electronics Letters, Volume 8, Issue 14, p. 364 –366
  • DOI:  10.1049/el:19720266
  • Type: Article
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  • p. 364 –366 (3)
    In the relaxation l.s.a. mode, the r.f. waveform across the loaded diode reaches very high voltages and then approaches, in part, the first cycle of a damped oscillation. The degree of damping depends on the loading of the circuit. It is shown theoretically that, for typical drive voltages, if the load is greater than G0/120 where G0 is the low-field device conductance, the voltage will not ultimately fall below threshold, accumulated space charge will not be dispersed and the diode will suffer avalanche breakdown owing to domain formation. Conversely, the loading must approach G0/120 to obtain maximum efficiency. These effects have been demonstrated in a pseudolumped circuit, using vapour-epitaxial metal-contacted devices. 400 W of peak power with 13.6% efficiency at 6.1 GHz has been obtained.
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Technique for compensating for reflector-antenna-surface errors with long correlation lengths
Technique for varying the conversion loss against frequency of a surface-wave transducer without apodisation

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