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Radio and Electronic Engineer

Issue 1 • Date July 1967

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Displaying Results 1 - 9 of 9
  • Economics and the engineer

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  • Amplitude limiting applied to a sensitive correlation detector

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    It is shown that the stability of a sensitive correlation detector can be improved by limiting the amplitudes of the voltages in either one or both input channels. The loss of output signal/noise ratio compared to an ideal multiplier-correlator is determined as a function of limiting level for both cases. The output signal/noise ratio of an unstable multiplier/correlator can be considerably less than the theoretical maximum. Thus, depending upon the source of the instability, it is possible to increase the output signal/noise ratio until an optimum value is reached by the technique of amplitude limiting. Further advantages of this technique are discussed in the paper. View full abstract»

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  • Mechanisms in gunn effect microwave oscillators

    Page(s): 17 - 30
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    Four microwave mechanisms found in Gunn diodes are discussed. Firstly, growing space-charge waves give a frequency dependent negative resistance which can be used to obtain amplification as well as to make oscillators. When any region or domain of high electric field is formed in a Gunn diode, three other microwave mechanisms are found: a current or voltage generator is created by the collapse of the domain if it drifts out of the diode at the anode contact; a negative resistance is sustained by the presence of the domain; finally, d.c. can be converted into r.f. by parametric mechanisms. This last effect is caused by the modulation of the circuit reactance due to the insertion and removal of the capacitance associated with the high-field domain. An equivalent circuit is discussed and is used to explain how these effects contribute to the various modes of oscillation exhibited by Gunn diodes. View full abstract»

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  • High-order multipliers without idlers

    Page(s): 31 - 38
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    This paper describes a theoretical and experimental investigation carried out in order to provide design information about highorder multipliers without idlers which utilize the approximate step-function voltage-capacitance relationship of step-recovery diodes. View full abstract»

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  • The practical design of interdigital and comb-line filters

    Page(s): 39 - 52
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    The design procedures for interdigital and comb-line filters are summarized and the theory of these filters extended to include various aspects of design and performance which are not covered in the literature. The basic design equations are modified to give unified sets of expressions relating the resonator capacitances directly to the filter specification, and the theory of these filters is extended to include group delay, high-power breakdown effects and precise centre-frequency synthesis. In addition, the factors contributing to in-band dissipation loss are considered, and a method of predicting this loss in terms of the unloaded-Q of a slab-line resonator is given. Finally, a method of suppressing unwanted harmonic responses is outlined. View full abstract»

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  • The direction of movement of F2 region perturbations

    Page(s): 53 - 59
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    A new method is described for measuring the direction of movement of F2 region perturbations from the changes of phase path due to travelling ionospheric perturbations recorded at three closely-spaced aerials. The results of the analysis using this method for 151 perturbations are presented. It is found that the direction of movement of perturbations with quasi-periods of about 15 minutes and maximum height changes of about 2¿3 km is within 230 to 250° to the east of north at a low-latitude station, Waltair. The direction of movement of these perturbations was found to be independent of the time of the day. View full abstract»

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  • The equivalent circuit of two-port antennae with an application to magic-T systems

    Page(s): 60 - 64
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    An equivalent circuit is presented for a two-port antenna immersed in the field of an external source. The circuit consists of admittances and current generators, and the value of the latter is particularly simple when the irradiating wave is a plane wave. The existence of a plane of symmetry also simplifies matters, particularly when the two output ports are connected to the series arms of a magic-T. View full abstract»

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