摘要:

The paper describes the development of a tr switch mounted in coaxial line for use at 200Mc/s. Two designs of tr switch emerged, each representing a balance of the conflicting design features required and a solution to the problem of sputtering.In one design, the sputtering is minimised by using an extended electrode area, and this provides a simple and rugged construction. However, this is somewhat at the expense of breakthrough and recovery time. The other design uses an impregnated tungsten electrode with a low work function to further reduce sputtering, and this gives an improved performance, particularly in arc loss and firing power, but it does result in a more complicated and less rugged structure.The application of d.c. bias reduces the recovery time in both designs of switch, particularly for the simpler version.A simple pass/fail test is described, which can be applied in the field when complicated test equipment is not available.

DOI:10.1049/piee.1964.0268

出版商:IEE    

年代:1964

数据来源: IET

摘要:

After a brief introduction to matched filters, a new method for their realisation, using magnetostrictive delay lines to generate sampled impulse responses, is described. The impulse response is determined by the distribution of remanent magnetism along the delay-line wire, and only one transducer coil is used. Investigations into the performance of the device as a matched filter are described.

DOI:10.1049/piee.1964.0269

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The insertion-loss method of design is used to develop further tables of element values for the double-terminated, inductively coupled, double-tuned interstage network, with equiripple insertion-loss characteristics corresponding to minimum passband return losses of 10, 15, 20, 25 and 30dB. In each case, the lower edge of the passband is varied from 0.1 to 0.95 in increments of 0.05, with the upper edge normalised to unity.

DOI:10.1049/piee.1964.0270

出版商:IEE    

年代:1964

数据来源: IET

摘要:

In fast logic systems many difficulties are involved in electrical logical interconnections, which in the fastest systems have to be by correctly terminated matched lines. Because the line impedance is necessarily low, it is difficult to meet the requirements of (i) a useful fan-out ratio, and (ii) digit voltages large enough to overcome interference and tolerances at the inputs of succeeding logic elements, without demanding considerable energy dissipation at each logic step. Some of these difficulties may be avoided by transmitting the digital information in the form of light, but the losses inherent in this process, and the large gain required to offset these losses, have hitherto precluded the realisation of fast optoelectronic digital systems.A method is proposed in which a large current gain is obtained by accelerating photoelectronsin vacuoand using their kinetic energy to generate electron-hole pairs in a semiconductor electron detector. The time delay associated with this gain is far smaller than would be introduced by other means.It is shown that an optoelectronic logic system using refinements of techniques already available should yield logic speeds comparable with the fastest so far reported for other methods, larger fan-in and fan-out ratios, and a power dissipation several times smaller. Foreseeable developments should permit substantial further increase in speed and reduction of power dissipation.

DOI:10.1049/piee.1964.0271

出版商:IEE    

年代:1964

数据来源: IET

摘要:

Concise mathematical formulas are developed for the input impedances, output impedances and transfer functions of ladder networks containing two kinds of elements only, namely resistance and capacitance or resistance and inductance or capacitance and inductance. A procedure is given for extending these formulas to the most general type of ladder network in which any series or shunt arm may contain all the three types of elements connected in any configuration. As examples of their application, the formulas are used to deduce the design equations of a phase-shift oscillator employing four- and five-section resistance-capacitance ladder networks.

DOI:10.1049/piee.1964.0272

出版商:IEE    

年代:1964

数据来源: IET

摘要:

Backward waves can propagate in an inhomogeneous waveguide of circular cross-section when the geometry and the properties of the materials are suitable. The phenomenon is related to a degeneracy of theH11andE11modes at cutoff, and this suggests where to look for the most pronounced effect. The behaviour of the group velocity is studied in detail, in the neighbourhood of the degeneracy, for a number of values of the guide radius. A discussion is given of the possibilities of applying the phenomenon to backward-wave amplifiers, travelling-wave masers, a frequency selector, a circular polariser, switching and phase compensation.

DOI:10.1049/piee.1964.0273

出版商:IEE    

年代:1964

数据来源: IET

摘要:

When a radiating source is immersed in a homogeneous plasma of infinite extent; an electroacoustic wave may be excited in addition to the usual electromagnetic wave. The electroacoustic wave becomes a longitudinal plasma wave in the far zone of the source.The case of a Hertzian dipole in a lossless plasma is considered first. The fields of both the electromagnetic (e.m.) and plasma modes excited by the dipole are explicitly obtained, and the e.m. and plasma components of the radiation resistance of a Hertzian dipole are determined. The case of a cylindrical-dipole antenna in a lossless plasma is investigated next. The far-zone fields of both the e.m. and plasma modes are explicitly obtained, and the e.m. and plasma components of the radiation resistance are then derived as functions of the antenna dimension and the plasma parameters. Finally, the case of a Hertzian dipole in a slightly lossy plasma is studied; the effect of collisions in a plasma on the radiation resistance of the immersed antenna is discussed.

DOI:10.1049/piee.1964.0274

出版商:IEE    

年代:1964

数据来源: IET

摘要:

Experimental procedures are developed for the determination of input impedance, gain and scattering cross-section of an antenna as a function of its load, from a minimum of three scattering amplitude measurements. The procedures involve terminating the antenna with a calibrated reactive load, whose variation causes a maximising and minimising of the antenna scattering cross-section; the loads associated with certain cross-sections are plotted on a Smith chart, and through geometrical constructions are related to input impedance; formulas are developed relating maximum and minimum cross-sections to antenna gain and cross-section. Experimental verification of the procedures is presented and their advantages and disadvantages are discussed.

DOI:10.1049/piee.1964.0275

出版商:IEE    

年代:1964

数据来源: IET

摘要:

This paper presents a technique for synthetising linear signal-processing antenna arrays using wideband elements and a matched filter. It is shown that, for signals with a finite spectrum, such arrays will consist of a far lower number of elements and have smaller overall dimensions than conventional arrays for single-frequency c.w. operation with similar radiation characteristics. The elements are, in general, unequally spaced, and the detailed design procedure depends upon the signal spectrum. Examples are included which denionstrate quite drastically the advantages of such signal-processing arrays. Comparison with single-frequency Dolph—Chebyshev arrays emphasises these advantages.

DOI:10.1049/piee.1964.0276

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The paper begins by considering the reliability of two low-power methods of measuring stray load losses: the first of these methods is the well known reverse-rotation test and the second a relatively unknown test called the d.c. excitation test. The development of a new and accurate full-load method of measuring stray load losses in squirrel-cage induction motors is then discussed, and the results obtained from this test are compared with the low-power test results. Fifteen motors in all were tested.The paper also deals with the effect on stray load losses of speed, current and the m.m.f. harmonic contents of the stator winding. The magnitudes of the measured stray load losses are compared with the amounts allowed by British Standard 269: 1927.

DOI:10.1049/piee.1964.0281

出版商:IEE    

年代:1964

数据来源: IET