摘要:

Several ferrite devices recently developed for systems applications are described. The behaviour and characteristics of extremely compact u.h.f. isolators based on new microwave techniques are reported. Faraday rotation and Y-circulators operating over wide temperature ranges and with broad frequency bandwidths are described. Also included are switches based on Faraday rotation, turnstile-junction and stripline-junction circulators. Strip and rectangular coaxial transmission-line phase shifters particularly suitable for antenna scanning applications are discussed. A discussion in terms of the intrinsic properties of ferrite materials is given that defines the frequency regions of operation for these phase shifters.

DOI:10.1049/pi-b-2.1962.0025

出版商:IEE    

年代:1962

数据来源: IET

DOI:10.1049/pi-b-2.1962.0026

出版商:IEE    

年代:1962

数据来源: IET

摘要:

A circular disc of gyromagnetic material, when placed between two infinite plane conductors and magnetized axially, can support cylindrical modes having no field variation in the axial direction. In terms of a superposition of some of these (radiating) modes the physical principle of the stripline circulator can be explained, at least tentatively.Moreover, from this theory some information can be obtained about the dependence of physical dimensions (such as disc radius and stripline width) on frequency, magnetic bias field and magnetization. Reference is made to the eigen resonances of the ferrite disc. Some experimental results are given and compared with the theory.

DOI:10.1049/pi-b-2.1962.0027

出版商:IEE    

年代:1962

数据来源: IET

摘要:

Various methods are described by which the usual TEM coaxial-line mode can be distorted to produce a region of circular polarization in which the non-reciprocal properties of ferrites can be exhibited. Three basic designs of isolator are given:(a) A coaxial-line construction with stub arms. Simple theory is given for this, as well as performance details. Information is given on models of two differing line sizes, together with a method of broad-banding the isolator.(b) An isolator in which the line is split and crossed in such a manner as to produce time and space quadrature of the r.f. fields. Performance figures of a practical model using printed-circuit techniques are given.(c) An isolator construction using a half-dielectric-filled coaxial line. The method of taper calculation and construction is described, and performance figures for the isolator are given.Gyrators and circulators have also been constructed:(d) A 90° gyrator using a partially dielectric-filled coaxial wave-guide. The method of mode transformation is described, together with results for a practical model. The performance of a 4-port circulator using this gyrator is predicted.(e) A compact triplate 3-port circulator is described. Attention is given to the important parameters, and the dependence of performance upon them is discussed.

DOI:10.1049/pi-b-2.1962.0028

出版商:IEE    

年代:1962

数据来源: IET

摘要:

In order to use ferrites to modulate microwaves efficiently maximum coupling must be obtained between the microwave field and the ferrite and this can be done conveniently by using a high-Q cavity. The paper presents the analysis and measurement of the behaviour of a ferrite rod in an H11ncylindrical resonant cavity with separate input and output ports. It is shown that the cavity behaves like a pair of coupled resonant circuits, the coupling being proportional to the magnetization of the ferrite rod. The power required for using the device as a modulator is calculated in terms of theQof the cavity and the microwave attenuation, and it is shown how the modulation power may be reduced by sacrificing bandwidth and output at the microwave frequency. The problem of introducing the modulating field into the cavity is discussed. Measured results are presented for a microwave frequency of 35 Gc/s, which suggest that the device could be used as a video modulator up to frequencies of the order of 70 Mc/s with a driving power of about 25W for 100% modulation, and with a minimum microwave attenuation of 3.5 dB.

DOI:10.1049/pi-b-2.1962.0029

出版商:IEE    

年代:1962

数据来源: IET

摘要:

Short notes on the mechanical arrangements of various storage drums, and the principles of storing and recovering digital information from such drums, are followed by a discussion on transducer design.An optimum transducer design is described, which is suitable for both writing-and reading-head functions. The characteristics of Mumetal and ferrite transducers are discussed, as well as the problems of mounting and screening.The preparation and performance of both nickel-plated and oxide-coated recording surfaces are described, and the results are compared, showing that oxide surfaces are more suitable when high-density storage is required.

DOI:10.1049/pi-b-2.1962.0031

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The thin magnetic film has now become a very attractive addition to the ferrite toroid and plate matrix as storage and switching elements in digital computers. Five types of film unit are being investigated:Nickel-iron vacuum evaporated on insulating and conducting substrates.Nickel-iron electrochemically deposited on conducting substrates.Nickel-cobalt chemically deposited on insulating substrates.Nickel-iron deposited by cathodic sputtering on insulating substrates.Ferrite films on insulating substrates or self-supporting.Of these, the first has been the most extensively examined. The rest are alternatives attempted as possible improvements over the first type. Advantages offered by thin-film storage units are small size, small power required for switching and very high switching speeds. The main disadvantage is the small Output signal of the film, making the design of sensing amplifiers used in the computer circuit more critical.

DOI:10.1049/pi-b-2.1962.0032

出版商:IEE    

年代:1962

数据来源: IET

摘要:

Of the alloys having a rectangular hysteresis loop, certain nickel-iron-molybdenum alloys are the most attractive for information-storage applications. The properties required of the material differ with the type of storage device.Two groups of alloys have been prepared by powder metallurgy; one containing about 4% molybdenum and the other about 12% molybdenum. These materials must be rolled to about 0.5 mil to achieve a reasonably rectangular hysteresis loop and fast switching; the best compromise between these two conflicting requirements is obtained with final reductions of about 50%. The coercivity can be made to have any value between 0.05 and 2 Oe by suitable final heat treatment. When measured with a maximum field of 1 Oe the squareness of the best 4% molybdenum alloy is 0.88 and the switching time is 0.7 μs; the 12% molybdenum is a little less square and has half the switching time.In any device in which a switching field of about 1 Oe is suitable (e.g. the shift register) both these materials are faster than ferrites. When a discriminatory action is required, alloy tapes can be used with very small fields but they switch more slowly.

DOI:10.1049/pi-b-2.1962.0033

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The simple theory behind the design of magnetic film matrices is presented, and it is shown that complete cycles representing switching operations can be traced out on diagrams of critical field values. Three known modes of operation are illustrated in the diagrams, and new ones are derived from the diagrams which use more than one film element per bit to combat troubles caused by film misorientation. The magnetization rotations expected in four modes are illustrated, together with the associated waveforms in the corresponding matrices. Figures of merit are derived for the tolerances to variations in digit current and in film orientation for the useful situation where the word current is high, both for the simplest theoretical model and for more realistic cases. The new modes of operation are found to be the most tolerant.

DOI:10.1049/pi-b-2.1962.0034

出版商:IEE    

年代:1962

数据来源: IET

DOI:10.1049/pi-b-2.1962.0035

出版商:IEE    

年代:1962

数据来源: IET