DOI:10.1049/pi-b-2.1960.0061

出版商:IEE    

年代:1960

数据来源: IET

DOI:10.1049/pi-b-2.1960.0062

出版商:IEE    

年代:1960

数据来源: IET

DOI:10.1049/pi-b-2.1960.0063

出版商:IEE    

年代:1960

数据来源: IET

DOI:10.1049/pi-b-2.1960.0064

出版商:IEE    

年代:1960

数据来源: IET

摘要:

Measurements have been made of the radiation patterns of typical aerials, such as would be used for domestic reception in the v.h.f. band, connected directly to a coaxial cable without the intervention of a balance/unbalance transformer. The vertical radiation pattern may be appreciably distorted, owing to the excitation of currents on the outside of the cable and the sensitivity to vertically-polarized interference originating near to and below the aerial may be increased. The distortion of the radiation pattern appears to be less serious with directional aerials. The use of a balance/unbalance transformer or a balanced feeder would be desirable, but unless the input circuit of the receiver is either balanced, or screened and unbalanced, no ideal solution exists.

DOI:10.1049/pi-b-2.1960.0067

出版商:IEE    

年代:1960

数据来源: IET

摘要:

The conventional representation of an electric circuit as a pattern of branches, nodes and meshes (topological graph) is historic. The less familiar representation as a set of contiguous rectangles, proposed by the author1in 1951 from a suggestion made by Hering2(1927), has many conceptual advantages;*not only does it represent the network pattern topologically but it displays other physical properties: the dual of the circuit is included; the element energies and co-energies (energy duals) are shown; current and voltage magnitudes are represented, etc. This rectangle representation of a planar circuit is briefly reviewed and its special application to non-linear circuits is explained.From simple geometrical symmetry of the rectangle diagrams it becomes immediately obvious that iterative structures (lattices, bridged-T, etc.) may be constructed from dual non-linear resistive elements having linear iterative impedances. If these can be constructed practically, they might be connected in cascade, without mutual interaction, as non-linear equalizers analogous to Zobel's constant-resistance phase-equalizers.The analogy to Zobel's networks is shown to be surprisingly complete, though the author can yet find no physical relation between these and the present non-linear networks.

DOI:10.1049/pi-b-2.1960.0068

出版商:IEE    

年代:1960

数据来源: IET

摘要:

Phase-shift keying (p.s.k.) is discussed as a modulation technique for transmitting digital data over radio circuits subject to fading. The modest bandwidth requirements of p.s.k. modulation suggest that it can not only alleviate spectrum crowding, but can also transmit traffic with fewer errors. The theoretical results presented here indicate, however, that the random phase perturbations inherent in fading radio signals cause unavoidable degradation in the performance of p.s.k. systems. Experimental data which partially support the theoretical results are cited, and comments relevant to the improvement of p.s.k. systems are included.

DOI:10.1049/pi-b-2.1960.0069

出版商:IEE    

年代:1960

数据来源: IET

摘要:

Several basic arrangements of delay unit, combining unit and feedback unit are shown to have amplitude/frequency response characteristics of the type which has given rise to the namecomb filter. Such filters are useful for the selection or rejection of a train of uniformly spaced regular pulses. The response of the most suitable configurations to such a train of pulses and to a Gaussian noise input is investigated with particular reference to the improvement in signal/noise ratio possible with this type of filter. The practical realization of such filters is discussed and the most suitable forms of practical comb filter are indicated, together with a brief discussion of their incorporation into a radar system.

DOI:10.1049/pi-b-2.1960.0070

出版商:IEE    

年代:1960

数据来源: IET

摘要:

Atmospheric noise received on a vertical aerial is compared with a locally-generated keyed signal to estimate the level at which the signal is 95% intelligible. This method was used in earlier high-frequency equipment and has been adapted for the range 15–500 kc/s.The apparatus and its method of operation are described. Results obtained at a number of sites are discussed in relation to more objective measurements. In particular, deduced noise powers are compared with existing world-wide predictions, revealing some differences.

DOI:10.1049/pi-b-2.1960.0071

出版商:IEE    

年代:1960

数据来源: IET

摘要:

An experimental 2-cavity klystron with a variable drift space has been constructed to investigate velocity-modulated electron beams. The operating frequency is 300 Mc/s. Previous experimental work with this valve has shown that the space-charge-wave theory accurately predicts both the optimum drift length and the output r.f. current, provided that small signals are used. Recent theoretical work on large-signal conditions has enabled some experimental results with large signals to be compared with calculations for similar, though not quite identical, conditions. Both the experiments and the theory show that the optimum drift length is considerably reduced when the input signal is large. The parameter that determines whether the signal is large is not merely the ratio of the modulating r.f. voltage to the beam accelerating voltage but is this quantity multiplied by the ratio of signal frequency to plasma frequency.

DOI:10.1049/pi-b-2.1960.0072

出版商:IEE    

年代:1960

数据来源: IET