Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 4, Issue 24, 29 November 1968
Volumes & issues:
-
Volume 59 (2023)
-
Volume 58 (2022)
-
Volume 57 (2021)
-
Volume 56 (2020)
-
Volume 55 (2019)
-
Volume 54 (2018)
-
Volume 53 (2017)
-
Volume 52 (2016)
-
Volume 51 (2015)
-
Volume 50 (2014)
-
Volume 49 (2013)
-
Volume 48 (2012)
-
Volume 47 (2011)
-
Volume 46 (2010)
-
Volume 45 (2009)
-
Volume 44 (2008)
-
Volume 43 (2007)
-
Volume 42 (2006)
-
Volume 41 (2005)
-
Volume 40 (2004)
-
Volume 39 (2003)
-
Volume 38 (2002)
-
Volume 37 (2001)
-
Volume 36 (2000)
-
Volume 35 (1999)
-
Volume 34 (1998)
-
Volume 33 (1997)
-
Volume 32 (1996)
-
Volume 31 (1995)
-
Volume 30 (1994)
-
Volume 29 (1993)
-
Volume 28 (1992)
-
Volume 27 (1991)
-
Volume 26 (1990)
-
Volume 25 (1989)
-
Volume 24 (1988)
-
Volume 23 (1987)
-
Volume 22 (1986)
-
Volume 21 (1985)
-
Volume 20 (1984)
-
Volume 19 (1983)
-
Volume 18 (1982)
-
Volume 17 (1981)
-
Volume 16 (1980)
-
Volume 15 (1979)
-
Volume 14 (1978)
-
Volume 13 (1977)
-
Volume 12 (1976)
-
Volume 11 (1975)
-
Volume 10 (1974)
-
Volume 9 (1973)
-
Volume 8 (1972)
-
Volume 7 (1971)
-
Volume 6 (1970)
-
Volume 5 (1969)
-
Volume 4 (1968)
-
Volume 3 (1967)
-
Volume 2 (1966)
-
Volume 1 (1965)
Volume 4, Issue 24
29 November 1968
Surface fields and near fields of a linear antenna
- Author(s): J. Galejs
- Source: Electronics Letters, Volume 4, Issue 24, p. 519 –520
- DOI: 10.1049/el:19680404
- Type: Article
- + Show details - Hide details
-
p.
519
–520
(2)
In a variational impedance formulation, antenna trial functions are modified to satisfy the edge conditions of diffraction theory. For a half-wave antenna, this provides a charge distribution with experimentally verified linear portions. The linearity of the charge distribution appears to be correlated with near-field fluctuations of the antenna.
High Q factor resonators in microstrip
- Author(s): P. Troughton
- Source: Electronics Letters, Volume 4, Issue 24, p. 520 –522
- DOI: 10.1049/el:19680405
- Type: Article
- + Show details - Hide details
-
p.
520
–522
(3)
A theoretical estimate has been made of the unloaded Q factor available from half and whole wavelength transmission-line resonators on an Al2O3 substrate. This takes ohmic losses into consideration as well as the radiation losses from various types of cavity termination. It is shown that optimisation of the Q factor of open-circuit terminated resonators demands a critical choice of substrate thickness and line characteristic impedance. Short-circuit terminated cavities generally have a substantially higher Q factor. A measurement technique has been developed, based on lightly coupled transmission probes. This has enabled practical measurements to be made of the unloaded Q factor of various microstrip cavities. Agreement with theory is satisfactory. Q factors up to 600 have been measured.
New experiments on the behaviour of the hybrid TEM-dual surface wave in a coaxial cable
- Author(s): H.M. Barlow and Mira Sen
- Source: Electronics Letters, Volume 4, Issue 24, p. 523 –524
- DOI: 10.1049/el:19680406
- Type: Article
- + Show details - Hide details
-
p.
523
–524
(2)
A new series of experiments, using a standing-wave method of measurement as well as a repetition of the previous resonant-cavity work, endorses the conclusion that a significant reduction of attenuation is possible, when the inner conductor of a coaxial cable is coated with a dielectric of higher permittivity than that of the surrounding medium, between the two conductors.
Differential equation for a linear combination of variables in a linear multivariable system
- Author(s): H.M. Power
- Source: Electronics Letters, Volume 4, Issue 24, p. 524 –526
- DOI: 10.1049/el:19680407
- Type: Article
- + Show details - Hide details
-
p.
524
–526
(3)
An algebraic procedure is described for extracting the differential equation governing a linear combination of state variables in the vector-matrix differential equation dx/dt=Ax+Bu. Computations are based on Krylov's algorithm for reduction of a matrix to rational canonical form, and on the Gram determinant test for linear independence of a collection of vectors.
Simple proof of unconditional controllability and observability
- Author(s): M.M. Milić
- Source: Electronics Letters, Volume 4, Issue 24, page: 526 –526
- DOI: 10.1049/el:19680408
- Type: Article
- + Show details - Hide details
-
p.
526
(1)
A direct proof using a frequency-domain argument is given of Chu's theorem on complete controllability and observability for every nonzero input and output matrix.
Magnetic tuning of coaxial IMPATT oscillators
- Author(s): J.A.C. Stewart
- Source: Electronics Letters, Volume 4, Issue 24, p. 526 –527
- DOI: 10.1049/el:19680409
- Type: Article
- + Show details - Hide details
-
p.
526
–527
(2)
Frequency tuning of an IMPATT coaxial microwave oscillator, using variation of susceptibility of a 5 Oe linewidth y.i.g. sphere, is described. A deviation sensitivity of 2MHz/Oe is determined experimentally. Qualitative explanation is offered for the discrepancy between this value and the theoretically predicted sensitivity.
Spectral-matrix factorisation
- Author(s): R.J. Kavanagh
- Source: Electronics Letters, Volume 4, Issue 24, p. 527 –528
- DOI: 10.1049/el:19680410
- Type: Article
- + Show details - Hide details
-
p.
527
–528
(2)
It is shown that a modification of Davis's method of spectral-matrix factorisation leads to a useful reduction in the effort required to obtain the desired factors.
Measurement of current pulses due to discharges in a gaseous cavity in solid dielectric
- Author(s): B. Salvage and O. Tapupere
- Source: Electronics Letters, Volume 4, Issue 24, p. 529 –530
- DOI: 10.1049/el:19680411
- Type: Article
- + Show details - Hide details
-
p.
529
–530
(2)
Initial current pulses, as measured with a sampling oscilloscope, rise to their peak value in a time ≲ 2ns. After repeated discharges, the current pulses greatly decrease in magnitude, but increase in duration; on resting, the magnitude tends to rise to its former value, but the longer duration persists.
Discharge repetition in an air-filled cavity in polythene under high direct electric stresses
- Author(s): S. Beg and B. Salvage
- Source: Electronics Letters, Volume 4, Issue 24, p. 530 –531
- DOI: 10.1049/el:19680412
- Type: Article
- + Show details - Hide details
-
p.
530
–531
(2)
Measurements, at ambient temperature, with electric stresses in the solid up to 110kV/mm approaching the electric strength of the dielectric, are described. At the highest stresses, the tendency to self extinction of the discharges disappears, and the larger discharges become more frequent with time.
State-dependent current source stretches timer pulse widths
- Author(s): K.S. Mehta and M. Venugopal
- Source: Electronics Letters, Volume 4, Issue 24, p. 531 –532
- DOI: 10.1049/el:19680413
- Type: Article
- + Show details - Hide details
-
p.
531
–532
(2)
A new principle of a state-dependent current source has been presented which can usefully be employed with conventional timer circuits to obtain large time delays. Two schemes employing this principle, one using a Schmitt trigger and the other using a modified monostabic, have been described.
Bulk-material device with current-controlled negative resistance
- Author(s): H.D. Rees
- Source: Electronics Letters, Volume 4, Issue 24, p. 532 –533
- DOI: 10.1049/el:19680414
- Type: Article
- + Show details - Hide details
-
p.
532
–533
(2)
Current-controlled negative resistance following avalanche breakdown is shown by structures of bulk ptype InSb up to 150°K and of ptype In(As, P) up to 300°K. The high speed of the InSb devices suggests applications as microwave sources or switches.
Evaluation of transient response
- Author(s): N. Ahmed and K.R. Rao
- Source: Electronics Letters, Volume 4, Issue 24, page: 533 –533
- DOI: 10.1049/el:19680415
- Type: Article
- + Show details - Hide details
-
p.
533
(1)
Image restoration by aperture-correction techniques
- Author(s): E.M. Deeley
- Source: Electronics Letters, Volume 4, Issue 24, p. 534 –536
- DOI: 10.1049/el:19680416
- Type: Article
- + Show details - Hide details
-
p.
534
–536
(3)
Improvement of television pictures de by aperture effects is at present performed by horizontal and vertical aperture correctors operating on the video signal. It is shown that true restoration can be more closely approximated to by a modified arrangement, and the limitations imposed by spatial noise are investigated.
Application of frequency-domain stability criteria to certain nonlinear position control systems
- Author(s): R.W. McGee
- Source: Electronics Letters, Volume 4, Issue 24, p. 536 –537
- DOI: 10.1049/el:19680417
- Type: Article
- + Show details - Hide details
-
p.
536
–537
(2)
Results are obtained by the construction of a quadratic form of Lyapunov function, following the method of McGee and MacLellan. A comparison with Fallside and Ezeilo shows that, for certain systems containing a nonlinearity which is a function of several variables, previously established sufficient conditions for stability are substantially weakened.
New criterion of realisability
- Author(s): S.C. Kak
- Source: Electronics Letters, Volume 4, Issue 24, p. 537 –538
- DOI: 10.1049/el:19680418
- Type: Article
- + Show details - Hide details
-
p.
537
–538
(2)
To check the physical realisability of a system, the Paley-Wiener criterion is usually employed. In the letter, an alternative criterion is put forward, which has the additional property of allowing the computation of the unrealisable part of the transfer function directly.
Correlation-multiplex data-transmission system
- Author(s): R. Barrett and J. Karran
- Source: Electronics Letters, Volume 4, Issue 24, p. 538 –539
- DOI: 10.1049/el:19680419
- Type: Article
- + Show details - Hide details
-
p.
538
–539
(2)
An integrated-circuit multichannel telegraph system is described, employing Boolean-logic multiplexing and correlation detection in place of conventional frequency-division-multiplexing (f.d.m.) techniques.
Class of discrete integrating operators
- Author(s): A.E. Durling
- Source: Electronics Letters, Volume 4, Issue 24, p. 539 –540
- DOI: 10.1049/el:19680420
- Type: Article
- + Show details - Hide details
-
p.
539
–540
(2)
A class of integrating operators is presented which assumes an interpolation which is an nth-order polynomial between the sample points and has n — 1 continuous derivatives at the sample points. It is shown that several classical numerical integration schemes and zform substitutes are special cases of this class.
Microwave amplification with GaAs avalanche diodes
- Author(s): H.J. Kuno ; J.R. Collard ; A. Gobat
- Source: Electronics Letters, Volume 4, Issue 24, p. 540 –542
- DOI: 10.1049/el:19680421
- Type: Article
- + Show details - Hide details
-
p.
540
–542
(3)
Experimental results obtained with an Xband reflection amplifier using vapour-phase epitaxial GaAs p–n junctions biased into avalanche breakdown are presented. Single-side-band noise figures of 17dB, power gains in excess of 30dB, and a high dynamic range have been repeatedly measured. The noise figures obtained with a large number of these diodes are significantly lower than those reported for Si or Ge diodes.
Enhancement of s.e.c. target gain in television-camera tubes
- Author(s): D. McMullan and G.O. Towler
- Source: Electronics Letters, Volume 4, Issue 24, p. 542 –543
- DOI: 10.1049/el:19680422
- Type: Article
- + Show details - Hide details
-
p.
542
–543
(2)
A temporary increase in the gain of an s.e.c. target has been found after the target has been flooded with imaging electrons while the reading beam is switched off. A qualitative theory to account for this enhancement is put forward. The production of negative images using this phenomenon is also described.
‘Punch-through’ transit-time oscillator
- Author(s): G.T. Wright
- Source: Electronics Letters, Volume 4, Issue 24, p. 543 –544
- DOI: 10.1049/el:19680423
- Type: Article
- + Show details - Hide details
-
p.
543
–544
(2)
It is shown that high-frequency negative resistance can be obtained in a space-charge-drift diode using ‘punch-through’ injection. Efficiencies for power generation of about 20% are estimated for the ideal structure. The device should be suitable for low-power low-noise applications.
Efficient frequency multiplication by odd factors without idlers
- Author(s): J. Fikart
- Source: Electronics Letters, Volume 4, Issue 24, p. 544 –546
- DOI: 10.1049/el:19680424
- Type: Article
- + Show details - Hide details
-
p.
544
–546
(3)
Antiparallel connection of two varactors in a multiplier as a means of efficient idlerless frequency multiplication by odd factors is discussed. For a tripler, the dependence of efficiency, output and dissipated power on input frequency is shown. A practical multiplier and its properties are described.
Simplified model for the domain dynamics in Gunn-effect semiconductors covered with dielectric sheets
- Author(s): R. Englemann
- Source: Electronics Letters, Volume 4, Issue 24, p. 546 –547
- DOI: 10.1049/el:19680425
- Type: Article
- + Show details - Hide details
-
p.
546
–547
(2)
A simplified model is proposed which describes the effect of the stray fields in dielectric surface layers on the dynamical behaviour of domains in thin Gunn-effect semiconductors. The stray fields cause an increase in domain capacitance and hence a decrease in build-up time which leads to larger n0L products for stable operation.
Identification of discrete linear scalar systems by minimisation of a parametric norm
- Author(s): J. Richalet and B. Gimonet
- Source: Electronics Letters, Volume 4, Issue 24, p. 547 –549
- DOI: 10.1049/el:19680426
- Type: Article
- + Show details - Hide details
-
p.
547
–549
(3)
A structural distance between a scalar process and its model is introduced, and it is shown that it can be used to advantage for identification. Although this distance is not known, it can be minimised by a particular algorithm. Examples of application and an appraisal of this method are given.
Identification of discrete multivariate systems by minimisation of a parametric norm
- Author(s): F. Lecamus and J. Richalet
- Source: Electronics Letters, Volume 4, Issue 24, p. 549 –550
- DOI: 10.1049/el:19680427
- Type: Article
- + Show details - Hide details
-
p.
549
–550
(2)
Identification of multivariate systems by use of a parametric distance between process and model is proved to be feasible. Geometric significance in a parameter space is given. An algorithm is proposed which is simple enough to be used online in real-time operation.
Most viewed content for this Journal
Article
content/journals/el
Journal
5
Most cited content for this Journal
-
Extreme multistability in a memristive circuit
- Author(s): Bo-Cheng Bao ; Quan Xu ; Han Bao ; Mo Chen
- Type: Article
-
Absorptive frequency selective surface using parallel LC resonance
- Author(s): Qiang Chen ; Liguo Liu ; Liang Chen ; Jiajun Bai ; Yunqi Fu
- Type: Article
-
Partial spectral search-based DOA estimation method for co-prime linear arrays
- Author(s): Fenggang Sun ; Peng Lan ; Bin Gao
- Type: Article
-
Experimental verification of on-chip CMOS fractional-order capacitor emulators
- Author(s): G. Tsirimokou ; C. Psychalinos ; A.S. Elwakil ; K.N. Salama
- Type: Article
-
54 Gbit/s OOK transmission using single-mode VCSEL up to 2.2 km MMF
- Author(s): G. Stepniak ; A. Lewandowski ; J.R. Kropp ; N.N. Ledentsov ; V.A. Shchukin ; N. Ledentsov Jr. ; G. Schaefer ; M. Agustin ; J.P. Turkiewicz
- Type: Article
