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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 11, Issue 2, 23 January 1975

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Volume 11, Issue 2

23 January 1975

Efficient damping method for least-squares algorithms
Design of multivariable systems using unity-rank state feedback: further results
Thermal characteristics of surface-wave recirculating loops on a y-cut quartz disc delay line
Electroluminescent GaAs–GaxAl1−xAs heterostructure diodes with negative resistance at low temperatures
Antenne spirales équiangulaires planes à réflecteur conique (Plane equiangular 4-arm spiral antenna with conical reflector)
  • Author(s): G. Grekou ; G. Dubost ; A. Madani
  • Source: Electronics Letters, Volume 11, Issue 2, p. 38 –40
  • DOI:  10.1049/el:19750030
  • Type: Article
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  • p. 38 –40 (3)
    On présente une étude expérimentale des principales caractéristiques de rayonnement d'une antenne à quatre spirales équiangulaires planes disposées au-dessus d'un réflecteur conique dont on fait varier l'angle au sommet. Un compromis entre gain et bande passante a été trouvé. We present experimental work giving the radiation characteristics of a plane equiangular four-arm spiral antenna with a conical reflector whose cone angle is varied. A compromise between gain and bandwidth is given.
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Generalisation of the self-tuning regulator
Simulation of a generalised self-tuning regulator
Semiempirical law relating cross-polarisation discrimination to fade depth for rainfall
  • Author(s): P.A. Watson  and  M. Arbabi
  • Source: Electronics Letters, Volume 11, Issue 2, p. 42 –44
  • DOI:  10.1049/el:19750033
  • Type: Article
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  • p. 42 –44 (3)
    A semiempirical law relating crosspolarisation discrimination (x.p.d.) to attenuation during rainfall is evolved by the comparison of theoretical predictions of x.p.d. (from a constant-canting-angle rainfall model) with 3.5 years of crosspolarisation data at 11 GHz. The concept of an equivalent mean, canting angle is proposed, and it is seen that the use of an equivalent mean canting angle of 4° in the semiempirical law gives an x.p.d. exceeded for 90% of the time. Typical x.p.d. values for deep fades are given by using an equivalent mean canting angle of 2 or 3°.
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Simple I/V model for short-channel i.g.f.e.t.s in the triode region
  • Author(s): L.D. Yau
  • Source: Electronics Letters, Volume 11, Issue 2, p. 44 –45
  • DOI:  10.1049/el:19750034
  • Type: Article
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  • p. 44 –45 (2)
    The standard 1-dimensional model for an i.g.f.e.t. in the triode region predicts values of the drain current ID that fall increasingly below experimental values as the channel is shortened or as the drain voltage VD is increased. However, a strictly 2-dimensional treatment results in prohibitive computation. A model is described that takes into account fringing fields at each end of the channel and which requires a relatively simple numerical solution of two nonlinear equations. Experiments on p channel i.g.f.e.t.s with gate lengths of 1.6 to 7.8 μm show that this model predicts I/V characteristics much better than does the standard 1-dimensional model which includes the bulk charge.
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S.A.W. fused-silica reflective-array compressor
  • Author(s): C. Lardat
  • Source: Electronics Letters, Volume 11, Issue 2, p. 46 –47
  • DOI:  10.1049/el:19750035
  • Type: Article
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  • p. 46 –47 (2)
    A surface-wave reflective-array compressor using edge-bonded transducers and a fused-silica substrate is described. A flat amplitude response over a 60 MHz bandwidth about a 100 MHz centre frequency has been obtained by weighting the groove depth. This is in good agreement with the theoretical calculated transfer function involving a δ function method. Insertion loss is 25 dB and a pulse-compression loop has shown a compression ratio of nearly equal to 1.800.
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New broadband balun
  • Author(s): H. Bex
  • Source: Electronics Letters, Volume 11, Issue 2, p. 47 –48
  • DOI:  10.1049/el:19750036
  • Type: Article
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  • p. 47 –48 (2)
    The letter describes a new balun composed of a modified ‘rat race’ with an open-circuit impedance at the uncoupled port. The advantage of this device is the great bandwidth, together with its very small dimensions. The performance of a layout on an alumina substrate is compared with theorotical predictions. For a midband frequency of 2.5 GHz, a bandwidth ratio of 52% and dimensions smaller than 1 cm2 on a 10 mil-thick alumina substrate are typical.
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Interpolation of discrete signals
Nonlinear quadrature model for a travelling-wave-tube-type amplifier
  • Author(s): P. Hetrakul  and  D.P. Taylor
  • Source: Electronics Letters, Volume 11, Issue 2, page: 50 –50
  • DOI:  10.1049/el:19750038
  • Type: Article
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  • p. 50 (1)
    A quadrature model for a travelling-wave-tube-type (t.w.t.) amplifier is developed. The model consists of two envelope nonlinearities, one in the inphase and the other in the quadrature path. Modified Bessel functions of 1st and 2nd order are used to approximate to these nonlinearities. This model is simpler than existing models and is found to yield an excellent agreement to the actual tube characteristics, so that analytic prediction of tube performance is readily accomplished.
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C/V curves for gate-controlled diodes in silicon on sapphire
Erratum: Logicfree data channels

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