摘要:

Five differentRCactive networks are considered, each of which produces a second-order low-pass transfer function. Two of the networks use positive feedback (one from an amplifier of nominally unity gain); two use negative feedback (one from an amplifier of nominally infinite gain); and the fifth uses a negative-impedance convertor. Equations are developed for the sensitivity of each circuit to its active and passive components, and these are compared with those for the sensitivity of a passiveLCRcircuit. The four active circuits using conventional amplifiers are also compared in terms of the total error in the transfer-function amplitude caused by given errors in the gain and feedback of the amplifier used.

DOI:10.1049/piee.1965.0213

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The principles of operation of nonlinear-interpolating-function generators are described. Nonlinear interpolators (n.l.i.s) comprise a plurality of nonlinear interpolating branches producing the desired output signal at a common output connection. The theory of the design of a simple halfsquarer is given, including a detailed consideration of both static and dynamic accuracy. N.L.I. squarers have an important application in n.l.i. multipliers, whose theory is explained.N.L.I.s provide simple function generators of good accuracy, fast response and excellent stability under ambient-temperature changes.A simple n.l.i. halfsquarer, using only two input branches, was found to have an overall low-frequency accuracy of ±0.7% of full output over a temperature range of 15–50degC, and a frequency response 2dB down, at 1 Mc/s. The provision of additional input branches improves the accuracy.

DOI:10.1049/piee.1965.0214

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The radiation characteristics of an axially oriented electric dipole situated at the centre of an infinitely long, cylindrical column of warm plasma are investigated. Two types of surface waves are excited along the plasma column, and their dispersion and power relations are examined. The radiation pattern in the far zone and the radiation resistance arising from the space waves are evaluated, and their dependence on the source frequency and the radius of the plasma column is discussed.

DOI:10.1049/piee.1965.0215

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The paper describes the need for a simple method of predicting the performance of a multisection microwave link. From the results of propagation measurements, a relationship is established between the worst-month fading distribution of a given microwave path, its path length and the roughness of the terrain. This relationship is then used to establish methods of predicting the worst-hour mean thermal noise and the thermal-noise levels exceeded for specified percentages of the worst month for a number of unequal microwave sections in tandem.

DOI:10.1049/piee.1965.0216

出版商:IEE    

年代:1965

数据来源: IET

摘要:

In a previous paper, suggestions were advanced for using a large-size rectangular waveguide, whose transverse dimensions are just less than λ×2λ, to increase the continuous-wave power-handling capability of a waveguide run. In the present paper, it is shown that, over a certain frequency range, the power handling can be further increased by operating the λ/2λ waveguide with the electric field directed parallel to the narrow face rather than the broad face, as previously. Trapped-mode resonance effects in such a system are investigated experimentally, and it is shown to be possible to suppress them using a long-slot directional coupler, which acts as a mode-selective attenuator.

DOI:10.1049/piee.1965.0217

出版商:IEE    

年代:1965

数据来源: IET

摘要:

When used as a frequency-mixing element, the tunnel diode has a performance which is superior in certain respects to that of existing mixer diodes at both u.h.f. and higher frequencies. The paper gives a brief outline of mixer theory and considers its application to the tunnel diode. The results of the analysis are compared with those of other authors, and the experimental results so far achieved are reviewed.

DOI:10.1049/piee.1965.0218

出版商:IEE    

年代:1965

数据来源: IET

摘要:

A subharmonic parametric oscillator, which uses the diffusion capacitance of a charge-storage diode, is described. The output of such a circuit may exist in one of two stable states, which are separated from one another in phase by πrad. Because of the nonlinear nature of the circuit, it is possible to change state within one cycle of the output voltage. The amplitude of the applied switching pulse is determined analytically in terms of the circuit parameters, and the analysis is confirmed experimentally.It would appear that this device could be made to operate as a logic element having a higher value for the bit-rate/pump-frequency ratio than existing parametrons.

DOI:10.1049/piee.1965.0219

出版商:IEE    

年代:1965

数据来源: IET

摘要:

Two new tubes for high-speed analogue multiplication at frequencies up to 200kc/s are described. The electrostatic field configurations required for multiplication are generated by special electrode systems which use plane electrodes, and are therefore relatively simple to construct and to mount with accuracy. The nonlinear error in prototype versions of these tubes is less than 2% of maximum output for one tube, and less than 3% for the other. The phase lag in the output with respect to either input is less than 2° for frequencies up to 200kc/s, and, with increased beam currents, the tubes are capable of operating at higher frequencies without an increase in the phase lag.It is anticipated that, with greater constructional care, an error of less than 1% of maximum output can be achieved.

DOI:10.1049/piee.1965.0220

出版商:IEE    

年代:1965

数据来源: IET

摘要:

Previous papers have described the principle of pole-amplitude modulation (p.a.m.), and its application to produce 2-speed single-winding squirrel-cage induction motors. The original theory and practice referred, specifically, to close-ratio speed changing only.This paper discusses p.a.m. on the basis of ampere-conductor distribution; and it extends its application to a considerable range of wide-ratio speed-changing induction motors. Two particular pole ratios, 4/1 and 5/1, are considered in detail, by way of example.In every case, a double-layer winding with all coils identical is used; and, in all but a very few applications, six control leads and very simple standardised control gear are required. Sample test results—particularly of the accelerating characteristics—are given, the machines being, in every case, fully up to normal industrial standards.

DOI:10.1049/piee.1965.0222

出版商:IEE    

年代:1965

数据来源: IET

摘要:

An experimental study of transient torques in induction motors, due to application of the supply, is described. The transient-torque recordings were obtained by means of a 2-phase induction generator, used as an accelerometer, and apply to the free-rotor, i.e. unloaded, condition. Point-on-wave switching was used to obtain selective transient-torque patterns. Results are given for 3-phase and single-phase motors. In the former case, the effects of nonsimultaneous switching, and of connecting the motor to the supply while the rotor is still rotating, are shown. The results confirm the assumption that the transient torques are due mainly to the interaction between transient asymmetrical flux and alternating currents.

DOI:10.1049/piee.1965.0223

出版商:IEE    

年代:1965

数据来源: IET