This report describes the development of a vhf-omnirange system, operating in the frequency band of 112 and 118 mc. The range furnishes magnetic-bearing information with respect to the range station, and provides definite track guidance between the station and any point within its service area. The omnirange produces two 30-cps signals: one is constant in phase and independent of the aircraft's position, and the other varies in relative phase directly in accordance with the magnetic bearing of the aircraft from the station. A phase-measuring device in the receiver enables the pilot to determine his magnetic bearing with respect to the station, and to select and fly a range course on any desired magnetic bearing. The accuracy of the system, including the receiver plus ground equipment, in operation at the Civil Aeronautics Administration Experimental Station, Indianapolis, Indiana, is approximately 1.5 degrees. The ground equipment has been in continuous operation for more than 3 years. The vhf omnirange has been selected as part of the common Civil-Military System, Transition Program, as recommended by the Radio Technical Commission for Aeronautics.

The Civil Aeronautics Administration VHF Omnirange

http://ieeexplore.ieee.org/iel5/19/2790/01032976.pdf

The development of impedence standards at KSRI

Design principles for gas-dielectric capacitors of high stability are discussed, with particular reference to parallel plate capacitors. A form of construction is proposed in which each of the two sets of plates is supported by a single mounting column and the mounting columns are secured to a single flat mounting plate. It is shown that for units of the highest precision it is desirable to have a 3-terminal construction in which the solid insulation is intercepted by the guard and shielded so that it serves a mechanical purpose only, so far as the direct capacitance is concerned.A marked improvement in stability is gained by hermetically sealing the capacitor in order to exclude changes in humidity and pressure.Constructional details and test results are given for two 1 000-μμF nitrogen-filled capacitors embodying these principles. The capacitance values have remained constant relative to one another within 1 part in 106 during the period of approximately two years following their construction. Close agreement between the temperature coefficients of capacitance and of linear expansion of the metal electrodes is taken as evidence that the capacitors are free from deleterious mechanical constraints.

A Fixed Gas-Dielectric Capacitor of High Stability

Another in a series of annual reports presented by the chairman of National Research Council's committee on electrical insulation, this article summarizes some of the principal advances in research work on gaseous, liquid, and solid dielectrics during the past year References are included to both fundamental scientific studies and practical research under service conditions

Recent Progress in Insulation Research

Maschinenwicklungen werden elektrisch, thermisch und mechanisch beansprucht, wobei alle drei Beanspruchungen gleichzeitig auftreten konnen.

Hochspannungsanlagen für Wechselstrom

The paper gives an account of (a) an investigation into the nature and causes of undesired changes in the capacitance and power factor of condensers, and (b) means of obtaining greater constancy. The principal results and conclusions are as follows:- The changes are almost entirely due to temperature variation. The thermal behaviour of condensers with solid dielectric is in general non-cyclic, and for a representative selection the temperature coefficients of capacitance ranged from -1800 to +200 parts in 10 6 per deg. C. The thermal behaviour of air-dielectric condensers is not cyclic in general, but more nearly cyclic than that of solid-dielectric condensers, and cyclic behaviour was obtained in some cases. The coefficients of a representative selection ranged from -65 to +150 parts in 10 6 per deg. C. Where the behaviour was cyclic, the capacitance coefficient was between 2 and 3 times that of the linear expansion of the metals used. An analysis of the causes of abnormally large coefficients showed that the variation of capacitance with air density is about 2 parts in 10 6 per deg. C. With entirely free expansion of metal plates, the coefficient is approximately that of the linear expansion of the metal, in accordance with simple theory. Variation of "fringe" and "stray" field with temperature has no appreciable effect on temperature coefficient. Change of residual internal stress in the metal plates and members with change of temperature is not in general a very important factor. Distortion due to temperature-gradients arising from inequalities of thermal characteristics of component parts is likely to be a significant factor in many cases. Variation of elasticity and moment of inertia with temperature is not significant. Unequal expansion of different parts may be a very important factor in producing large coefficients, particularly if the one set of electrodes is not quite symmetrical with respect to the other (i.e. unequal air-gaps). Even where con

https://ieeexplore.ieee.org/iel5/5245479/5245625/05245643.pdf

The electrical stability of condensers

This paper describes a novel method of feeding the spaced-aerial system of a radio beacon transmitter, which has arisen from the consideration of the possibilities of the application of the Adcock-aerial principle to such a beacon. A brief discussion is given of the limitations of the ordinary rotating-coil goniometer arrangement for such a beacon when the transmitted power is high. The alternative method described utilizes two power amplifiers to feed the two pairs of spaced aerials. These two amplifiers are supplied with radio-frequency voltages by means of a mechanical controller which automatically provides the required time/voltage variations. A description is given of this controller, together with its application to the problem of exciting the two amplifiers. It is shown that such a controller can fulfil the requirements of the excitation apparatus, and it is concluded that the system described would be suitable for incorporation in a full-size rotating radio beacon for marine navigational purposes.

http://ieeexplore.ieee.org/iel5/5308791/5316940/05316946.pdf

A method of exciting the aerial system of a rotating radio beacon

The paper describes the improvements in the technique of radio-receiver testing that have been made at the National Physical Laboratory. The arrangements now used for this purpose having been described in detail in Part 1, a proposed specification of methods of testing broadcast receivers is given in Part 2, together with experimental results obtained on such receivers. This specification is examined as to its applicability to the relative comparison of widely different types of receivers, and a classification is suggested so as to diminish the number of tests which it is necessary to make in order to assign a figure of merit to a particular receiver.

H.A. Thomas

Papers

The electrical stability of condensers

A method of exciting the aerial system of a rotating radio beacon

Developments in the testing of radio receivers