摘要:

Ferromagnetic relaxation measurements in single-crystal yttrium-iron garnet (YIG) are given over the range of 4.2° to 300°K. This is a report on the present status of YIG in which care has been taken to remove the extraneous rare-earth impurity ions and ferrous impurity ions. The measurements are reported in terms of the linewidth, ΔHk→0, of long-wavelength spin waves, which has been found to be approximately equal to the intrinsic linewidth of the uniform precession. ΔHk→0is related to the spin lattice relaxation time by the following: ΔHk→0≃ 1/γT10. The values of ΔHk→0were obtained using the parallel pumping technique, in which spin waves of known wavelength are generated at one-half the microwave frequency. A discussion is given of the usefulness of YIG in low-frequency microwave devices, low-temperature microwave power limiters and the Denton ferromagnetic amplifier.

DOI:10.1049/pi-b-2.1962.0013

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The paper describes the propagation behaviour of a circular wave-guide filled with a longitudinally magnetized ferrite. It is shown that, in a certain range of applied magnetic field and frequency, a slow backward wave can propagate. The dependence of the propagation coefficient of this mode on magnetic and dimensional parameters is determined. Experimental evidence in support of the theory is given, and possible applications of the phenomena to backward-wave tubes and filters are discussed.

DOI:10.1049/pi-b-2.1962.0014

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The theory of ferromagnetic resonance at high peak-power levels is briefly reviewed. Experimental results (mostly on polycrystals) concerning the threshold r.f. magnetic field and its dependence on composition, porosity, frequency, sample shape and temperature are presented. The data are in good qualitative agreement with recent theories of ferromagnetic relaxation. The relevance of the experimental results to device applications is pointed out.

DOI:10.1049/pi-b-2.1962.0015

出版商:IEE    

年代:1962

数据来源: IET

摘要:

A descriptive treatment is given of the lower-order ferrite-filled circular waveguide modes in terms of the bi-refringent character of the propagation. It is shown that under suitable conditions of d.c. magnetization the ferrite-filled guide can only support certain modes when its radius is less than a given value. These inverse cut-off modes are investigated in some detail, it is shown that their group velocity is negative and typical field patterns are illustrated. Experimental results are presented which confirm the major points of the theory and show reasonable quantitative agreement.

DOI:10.1049/pi-b-2.1962.0016

出版商:IEE    

年代:1962

数据来源: IET

摘要:

It is shown that in the neighbourhood of cut-off in an inhomogeneous waveguide, a considerable amount of energy travels in the negative direction, i.e. in the direction opposite to that of the wavefront. It has previously been shown that in the neighbourhood of cut-off it is possible for the group velocity to be negative; under these circumstances the negative power exceeds the positive power. This question is discussed, and a new concept of waveguide Q-factor is introduced.

DOI:10.1049/pi-b-2.1962.0017

出版商:IEE    

年代:1962

数据来源: IET

摘要:

Some substitutions have been carried out in yttrium-iron garnet (Y3Fe5O12) which have a marked influence on its properties. Small amounts of calcium decrease losses in the permeability in the frequency range 104–106c/s. The same can be accomplished by a small iron deficiency or a very careful method of preparation. Iron excess or substitution of tetravalent ions such as Ti4+or Si4+for iron gives rise to high losses in this frequency range. Combined substitutions of a divalent ion and a tetravalent ion such as Ca + Si and Ca + Ti for Y + Fe can be carried out in higher concentrations. The low-temperature magnetic moment decreases with the amount of silicon and increases with the amount of titanium. In the latter case the l.f. permeability increases to over 400. The losses in the kilocycle per second range can be reduced again with a small extra amount of calcium.The ferromagnetic line widths at 3cm of several samples have been measured and are usually found to lie between 50 and 100 Oe.The resistivity of nearly all samples is higher than 107Ω-cm.

DOI:10.1049/pi-b-2.1962.0018

出版商:IEE    

年代:1962

数据来源: IET

摘要:

From experience gained with plugs and sockets used in electro-mechanical telephone-switching apparatus and further experience of their use in association with electronic equipment, the necessity to improve their performance and reliability soon became apparent. Extensive research into the study of materials has led to the formation of a test specification which has the objective of determining plug and socket reliability for an anticipated usage of 30 years. This specification is given in an Appendix. Two designs satisfying this specification are outlined.

DOI:10.1049/pi-b-2.1962.0020

出版商:IEE    

年代:1962

数据来源: IET

摘要:

A connecting socket is described which has been developed for use with component group boards using printed wiring. Precious-metal contacts are employed. Connections to the board are made by operating a cam member after the board has been inserted, thus avoiding damage to the contact surfaces due to repeated insertion and withdrawal. The group board can be disconnected from the rest of the equipment by releasing the cam member, and arrangements can be made for this to be done automatically in cases of circuit failure.

DOI:10.1049/pi-b-2.1962.0021

出版商:IEE    

年代:1962

数据来源: IET

摘要:

In switching equipments using mainly electronic components, it is sometimes convenient to make use of relay contacts, for instance as boundary components when inter-working with electro-mechanical systems; but conventional relays do not fit comfortably into equipments designed for the mounting of electronic components. For such uses a new electromagnetic relay has been developed which is built on to a group board using printed wiring.

DOI:10.1049/pi-b-2.1962.0022

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The increasingly stringent environmental requirements associated with military airborne electronic equipment have led to some important changes in plug and socket designs.The paper reviews some recent connector designs incorporating high-temperature resilient insert materials and removable crimped contacts, which have improved performances over conventional connectors with rigid inserts and soldered contacts. A rack-and-panel connector with low insertion and withdrawal forces is described, and some comments are made on the requirements for printed-circuit connectors. Some aspects of current connector specifications in respect of contact-resistance measurement and moisture-sealing tests are discussed.

DOI:10.1049/pi-b-2.1962.0023

出版商:IEE    

年代:1962

数据来源: IET