摘要:

It is well known that phase errors introduced during the formation of synthetic antenna apertures and in the data-processing stages of pulse-compression radars degrade system performance. Expressions are presented from which the upper bounds of the degradation effects of small arbitrary phase errors on the azimuth resolution of synthetic apertures and the range resolution of pulse-compression radars can be calculated. It is not necessary to know the exact phase-error function; only the peak phase deviation need be given or estimated. These expressions allow the use of amplitude weighting factors for sidelobe reduction, and the effect of these factors on resolution degradation in the presence of phase errors is exhibited.

DOI:10.1049/piee.1964.0224

出版商:IEE    

年代:1964

数据来源: IET

摘要:

A method is described of phase-correcting a rectangular horn, whose H plane aperture is of the order of a wavelength or less, to obtain a uniform phase at the aperture. This is achieved by varying the guide wavelength within the horn, resulting in a slight taper in the H plane, and the shape so obtained is very suitable for electroforming. Results are given for an X band horn and show a great improvement in radiation pattern compared with an uncompensated horn.

DOI:10.1049/piee.1964.0225

出版商:IEE    

年代:1964

数据来源: IET

摘要:

An integral equation is found for the currents on a pair of symmetrical inductive strips in a rectangular waveguide, and is solved by known techniques to the quasistatic approximation. The integrals involved in the formula for the reactance presented to the waveguide are expressed in terms of elliptic integrals, and by a comparison of the result with the known result for a single inductive strip, the mutual inductance between a pair of strips in a waveguide is deduced.

DOI:10.1049/piee.1964.0226

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The transistor can be used as a switch, but its operating characteristic departs from the ideal by having a finite leakage current when open and an effective contact potential when closed. These effects, and the limitations they impose in use with precise analogue-digital convertors, are discussed.Types of circuit in which the transistor can be used are described, and it is suggested that it is possible to achieve a resolution and accuracy, when using the transistor switch, comparable with those obtainable with a conventional potentiometer.

DOI:10.1049/piee.1964.0227

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The nature of minority-carrier storage effects in an ideal planep-njunction are considered with particular reference to the shape of the reverse-current pulse that appears when the device is switched from forward to reverse bias. By approximating to this, a modulating function is formulated for a resistively terminated single-diode shunt modulator switched by a squarewave carrier, and the variations of insertion and conversion losses with frequency are calculated for a typical circuit. The performance of the modulator may be improved by three techniques whose values are assessed with particular reference to loss stability with changes in the diode parameters. The applicability of the theory to practical diode types is considered and the problem of sinewave switching outlined.

DOI:10.1049/piee.1964.0228

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The paper discusses a means by which the bandwidth limitations of synchronous tuned amplifiers may be overcome without recourse to configurations that yield excessive overshoot with impulsive inputs. Design tables and graphs are given for amplifiers up to the tenth order for different amounts of overshoot.

DOI:10.1049/piee.1964.0229

出版商:IEE    

年代:1964

数据来源: IET

摘要:

After giving particulars of the equipment and essential data for the French telecommunication-satellite station at Pleumeur-Bodou, the author gives a description of some of the principal results obtained during tests with Telstar I.Acquisition conditions were always excellent, and tracking proved to be very accurate, thus ensuring continuity of the telecommunication link.The experiments comprised joint tests, with one-way and two-way links, and technical tests. The results of the latter, described in the paper, were concerned with finding received-signal power, noise power at radio frequencies, thermal noise generated in the transmission channel, and distortion.

DOI:10.1049/piee.1964.0230

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The magnitudes of interactions between adjacent storage cells aligned along the easy-axis direction have been measured for various values of easy-axis skew and cell spacing, for both continuous film and film spots on aluminium substrates. Interactions are significantly smaller when film spots are used in place of continuous film. Experiments designed to establish the various causes of interactions with film spots and continuous film are described. Some observed effects due to stray fields have magnitudes five times those expected from simple theory. The comparatively large distances over which interaction effects occur in continuous film is attributed to domain propagation during the writing operation, giving variable demagnetising fields and variable proportions of flux linked by the sense conductor.

DOI:10.1049/piee.1964.0231

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The paper deals with invertors working over a considerable range of frequency and commutated by static capacitors. It reports a preliminary investigation of a circuit in which clamping diodes constrain the capacitors to hold their charges at their maximum value until next required for commutation.

DOI:10.1049/piee.1964.0235

出版商:IEE    

年代:1964

数据来源: IET

摘要:

A new type of reluctance machine is described in which, briefly, the radial poles of a conventional machine are replaced by circumferential segments. Working from the flux distribution in the air gap, general equations for the synchronous performance of reluctance machines are developed. These are used in a comparison of the new and conventional machines, and it is shown that the new machine has torque and power-factor characteristics which are superior to those of the conventional one.The air-gap flux distribution in the new machine exhibits unusual characteristics, and to discuss them precisely the ideas of m.m.f. have to be abandoned, those of magnetic potential being employed instead. Expressions are developed for the direct- and quadrature-axis reactances, and values computed from these are found to be in good agreement with values measured for a range of experimental machines.Though attention is devoted chiefly to fixed, normal-frequency operation, consideration is also given to machine performance under varying-frequency and direct-current conditions. In particular, it is shown that, under d.c. or low-frequency conditions, the output torque is directly proportional to the difference between the direct- and quadrature-axis reactances.Additionally a new method for the experimental determination of the axis reactances of salient-pole machines is described. This is based upon the theory of the impedance and current circle diagrams of reluctance machines which are also developed.

DOI:10.1049/piee.1964.0237

出版商:IEE    

年代:1964

数据来源: IET