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Radio and Electronic Engineer

Issue 3 • Date March 1966

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Displaying Results 1 - 7 of 7
  • What does R & D cost?

    Publication Year: 1966 , Page(s): 129 - 130
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (133 KB)  

    First Page of the Article
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  • Wideband coaxial variable attenuators using p-i-n diodes

    Publication Year: 1966 , Page(s): 131 - 144
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1404 KB)  

    Using a conventional equivalent circuit for a p-i-n diode, a computer program has been written which permits the compilation of data for use in designing a coaxial wide band variable attenuator. Procedures are outlined leading to design of voltage controlled attenuators whose performance over an octave within 1 to 10 Gc/s compares very favourably with the best commercially available passive attenuators. The procedures have been applied to specific cases and attenuators constructed. Their performance follows closely design data. The compiled data can also be used to design strip line attenuators and levellers. View full abstract»

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  • Acoustic amplification in semiconductors

    Publication Year: 1966 , Page(s): 145 - 155
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1800 KB)  

    If the application of semiconductors is to be extended to microwave frequencies, the limitations due to electrode capacitance and transit time must be overcome. To a certain extent this can be done by reducing junction size and using majority carriers where possible. However a muchmore sophisticated way of overcoming these difficulties is to try to realize in semiconductors the type of continuous interaction obtained in travelling-wave tubes. In the paper the present state of the art on acoustic amplification in semiconductors is reviewed. Although net gain at microwave frequencies has not yet been obtained, the experiments at lower frequencies have given some general indications about the feasibility of achieving this. The main problems lie in coupling into the crystal in such a way that the insertion losses are minimized and the shape of the acoustic wavefront within the crystal is not disturbed. The amplifiers described use quartz transducers to couple into and out of a CdS crystal. Recently, deposited CdS transducers have been operated at X-band for this type of application. This suggests that there are reasonable chances of making low loss delay lines and ultimately amplifiers for microwave applications. The importance of the acoustic amplifier as a diagnostic tool leading to a better understanding of other microwave phenomena in semiconductors is discussed briefly and the current instabilities in CdS which show similarities to the Gunn effect are described. View full abstract»

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  • Measurement of phase errors in the pilot-tone system for stereophonic broadcasting

    Publication Year: 1966 , Page(s): 157 - 160
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    In the pilot-tone system for stereophonic broadcasting, any small phase error of the pilot signal may be deduced from a waveform display of the multiplex signal, when using an appropriate modulating signal. An expression is derived for the error in terms of characteristics of the display, and a simple approximation is also given. View full abstract»

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  • An ultrasonic to electronic image converter tube for operation at 1.20 Mc/s

    Publication Year: 1966 , Page(s): 161 - 170
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1867 KB)  

    From 1949 to 1954 a programme of work was undertaken into the design of a cathode-ray image converter tube for transforming a plane section through a continuous-wave ultrasonic field to a television picture. Eleven different types of high-vacuum sealed-off experimental tubes were investigated. The final tube had a resonant quartz front-plate 5.7 cm diameter and operated at 1.20 Mc/s with a threshold acoustic sensitivity of 7 × l0¿7 watts/cm2. The overall acuity was 1 mm on the front-plate and the resulting picture appeared on a monitor cathode-ray tube at 16¿ frames per second with 110 lines per frame. This tube is compared with those reported by other workers since 1954. View full abstract»

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  • Seismic data acquisition and processing equipment for Edinburgh Royal Observatory

    Publication Year: 1966 , Page(s): 171 - 180
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1252 KB)  

    The paper deals with two main subjects: a set of portable recorders for field work, and a data-processing centre for collecting and analysing seismic recordings. The portable field recorders use frequency modulated recording on magnetic tape to handle the wide range of frequencies and amplitudes involved in seismic signals. Advantages and problems of mobile array stations are outlined, and the system design considerations for the recording equipment are discussed in detail, with a brief description of e units and their performance. The equipment and operation of the data laboratory are discussed, covering the following functions: (i) Playback of analogue tapes, (ii) Building of a library of events, (iii) Preparation of data for computer input, (iv) Playback of computer output, (v) Simplified processing of data. Proposals are put forward for a special-purpose digital processor, using the existing core-store memory system in conjunction with additional addressing and read-out facilities to perform processing with lags. View full abstract»

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  • The performance of backward diodes as mixers and detectors at microwave frequencies

    Publication Year: 1966 , Page(s): 181 - 191
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1344 KB)  

    The physical properties of a backward diode, together with the parameters of a microwave mixer and low-level detector are briefly reviewed, indicating the choice of a bonded-contact structure and n-type germanium. The microwave performance of such a diode is discussed with particular emphasis on optimizing the diode for low-level detector and Doppler mixer applications. Results of r.f. performance at X-band frequencies are illustrated. These show that bonded backward diodes may be fabricated with improved detector and Doppler mixer characteristics compared with conventional point-contact microwave diodes. Further, the desirability to optimize their characteristics for a particular application is examined. Zero-bias tangential sensitivities of ¿62 dBm (1 Mc/s video bandwidth) have been achieved. The low-frequency noise properties of the backward diode indicate a potential receiver noise figure performance of about 16 dB at 3 kc/s intermediate frequency. The ability of the bonded backward diode to operate satisfactorily as a mixer (i.f. = 45 Mc/s) with very low local-oscillator power is shown. Finally, the performance of a bonded backward diode under development primarily as a detector is discussed. Measurements at zero bias indicate tangential sensitivities of ¿56 dBm (1 Mc/s video bandwidth) and video impedance about 800 Cl, whilst maintaining a mixer performance of about 8 dB. Further, this performance is shown to be substantially independent of temperature. The resistance of these devices to damage by electrical overloads is shown to be comparable with conventional point-contact microwave diodes. View full abstract»

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