摘要:

The types of 3-frequency parametric upconvertors that have useful amounts of gain whilst being conjugately matched at both input and output terminals are reviewed. A detailed analysis is undertaken of 4-frequency upconvertors having similar properties. It is shown to be necessary for all such 4-frequency convertors, under high-gain conditions, to have certain properties in common. In all cases, the admittance looking into the idler terminals will have a negative-conductance component, which will approach in magnitude to the conductance of the idler termination as the gain of the convertor is increased. The admittances looking into the input and output terminals, on the other hand, are independent of any increase in gain obtained by varying the idler termination. Possible circuits of this type are discussed, and it is shown that convertors using both nonlinear inductance and capacitance, and also convertors using a double-pumped nonlinear capacitor, are both, in principle, realisable.

DOI:10.1049/piee.1965.0074

出版商:IEE    

年代:1965

数据来源: IET

摘要:

A method of finding a cavity coupling factorQxfrom the separation in wavelength between branches of tuning curves obtained by moving a short circuit in the feeder is described. This is complementary to a derivation from slopes proposed earlier. The alternative method is suitable over a large range ofQx(from about 30, where the formulas obtained forQxare least accurate, to 105or more). The highest value ofQxthat can be resolved is limited by losses in the cavity, feeder or short circuit.Experimental results obtained for a magnetron coupled to a waveguide are given, andQxfound by the above method is compared with that derived from standing-wave measurements. Good agreement in the values ofQxwas obtained.

DOI:10.1049/piee.1965.0075

出版商:IEE    

年代:1965

数据来源: IET

摘要:

It is shown that the minority-carrier-storage phenomenon may be utilised to achieve a variation in the mark/space ratio of the switching function in rectifier modulators. In a number of such modulators this variation results in a decrease of conversion loss, and these circuits are examined in detail. Differences in performance with square-wave and sine-wave carriers are considered, and the performance of a practical double-tuned modulator using OA200 diodes is reported.

DOI:10.1049/piee.1965.0076

出版商:IEE    

年代:1965

数据来源: IET

摘要:

A method of measurement of the complex permittivity of a semiconductor, in which a sample is introduced into a rectangular waveguide by means of insulated slots in the broad walls, is discussed. The corrections required to relate the behaviour of such a system to that of an idealised structure, which has a convenient theoretical solution, are described, and details are given of a microwave bridge circuit suitable for the measurement of the propagation coefficient of an inhomogeneously filled waveguide section.

DOI:10.1049/piee.1965.0077

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The development of coupled-transmission-line theory and applications has extended the bandwidth of certain microwave components to one decade or more. A review of the theory is presented in the most simple general form, which enables the effects of tolerances and perturbations to be calculated. A survey of available coupled-line configurations is presented, including a new printed re-entrant type, with, in some instances, more accurate formulas than those available in the literature. The theoretical aspects of this work are substantially complete, but there are practical difficulties associated with obtaining good directivity and higher-frequency devices.

DOI:10.1049/piee.1965.0078

出版商:IEE    

年代:1965

数据来源: IET

摘要:

A pure surface wave requires, in principle, unbounded space outside the supporting surface, thus permitting the field in the transverse plane to decay, without obstruction, to zero at an infinite distance from the surface. Such a wave cannot therefore be contained within a screen, unless the bounding surface matches precisely the field impedance at the point of its location. A surface of this kind must have capacitive reactance and a small negative resistance, which implies a subsidiary generator. A second surface wave, supported on the inside of the screen, can be set up to satisfy the boundary conditions, and the paper discusses arrangements that should meet the requirements, enabling full or partial screening to be achieved. Moreover it appears that the dual surface wave proposed may have a lower attenuation in a straight guide than the corresponding TEM mode.

DOI:10.1049/piee.1965.0079

出版商:IEE    

年代:1965

数据来源: IET

摘要:

High-density low-effective-mass plasmas in semiconductors allow plasma and cyclotron frequencies in the ultramicrowave range. It is proposed that the birefringence of these magnetoplasmas be utilised for gyratory devices such as circulators, isolators etc. at millimetre wavelengths. The conditions for the feasibility of these devices are discussed and are shown to be satisfied in practical cases. Experiments are described that demonstrate the existence of the circularly polarised semiconductor-plasma waves necessary for these devices.

DOI:10.1049/piee.1965.0080

出版商:IEE    

年代:1965

数据来源: IET

摘要:

Echoes are a well known form of impairment in television reception, but precise information on the subjective effect they cause has been scanty, and the limits for echo in specifications of television transmission systems have been set on a somewhat arbitrary basis. Using a previously proposed quality-grading method, tests have therefore been made of the effect of single undistorted echoes, having delays in the range 1–13μs, on still monochrome 625-line pictures typical of scenes in television broadcasting.The magnitude of echo corresponding to a given quality of picture decreases by about 5 dB as the delay is increased from 1 to 13μs. The effect of variation of delay over the range 5–13μs is less than 1dB; within this range, when echo-sensitive pictures are viewed under specified conditions, 50% favourable opinions are obtained with a signal/echo ratio of 23dB and 95% favourable opinions with a ratio of 28dB.

DOI:10.1049/piee.1965.0081

出版商:IEE    

年代:1965

数据来源: IET

摘要:

This paper describes the advantages that accrue from the use of an electronic beam-positioning radar system for both searching and tracking a complex target environment. It is also shown that the principal properties of such a system may be achieved using a radar system with transmitting and receiving beams scanning continuously at different rates. This technique results in the same power-distribution efficiency, but less efficient time utilisation, compared with an ideal beam-positioning radar.

DOI:10.1049/piee.1965.0082

出版商:IEE    

年代:1965

数据来源: IET

摘要:

This paper describes methods for enabling the directional pattern of a cylindrical array to scan continuously and repetitively through 360° by electronic means. This requires that the circular aperture distribution corresponding to the far-field directional pattern should be subjected to rotation relative to the fixed array. Methods are described for independent control of the amplitude and phase of the aperture distribution in order to synthetise suitable forms of directional pattern. Certain theoretical and practical limitations on the proposals are also discussed. The techniques are applicable, in principle, to both transmission and reception; a brief discussion of the relevance of the proposals to radar and sonar is also given.

DOI:10.1049/piee.1965.0083

出版商:IEE    

年代:1965

数据来源: IET