By Topic

Radio and Electronic Engineer

Issue 5 • Date May 1981

Filter Results

Displaying Results 1 - 12 of 12
  • The university of surrey's satellite project

    Page(s): 199 - 202
    Save to Project icon | PDF file iconPDF (670 KB)  
    Freely Available from IEEE
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Human factors of v.d.u.s

    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (167 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Techniques for utilization of hexagonal ferrites in radar absorbers. Part 1: Broadband planar coatings

    Page(s): 209 - 218
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1307 KB)  

    The lack of suitable materials having permeabilities (¿r) greater than unity at microwave frequencies has previously made it difficult to design thin coatings of broadband radar absorbersat this frequency range. A possible solution is to utilize the hexagonal ferrites that exhibit significant ¿rvalues (¿5) over narrow frequency bands and this paper investigates methods of deploying this material to design thin broadband microwave absorbers. Several techniques are evolved involving layering of the materials and staggering of the material electrical parametersand dimensions to achieve a good match ofthe incident waves. The computed results are substantiated by measurements of the manufacturedmaterials; measurement techniques and details of the materials used are given in appendices. It is established that a planar absorbent sheet having a reflection loss > 10 dB over 5¿20 GHz is realizable within a practically acceptable thickness. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Techniques for utilization of hexagonal ferrites in radar absorbers. Part 2: Reduction of radar cross-section of h.f. and v.h.f. wire antennas

    Page(s): 219 - 225
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (857 KB)  

    Coatings of hexagonal ferrites on a wire antenna reduce its back-scattering radar cross-sections (r.c.s.) at microwave frequencies without causing significant deterioration of its radiation efficiency at the h.f. and v.h. communication bands. The back-scattering r.c.s. of an infinitely long conducting cylinder coated with a multilayer of hexagonal ferrites is derived and the result modified to take account of the finite length of a monopole antenna. Computed results for layered coatingsare presented to demonstrate the improvement in the microwave absorption bandwidth obtainable for a given coating thickness. It follows that the technique is best applied with all material and geometric parameters having tapered distribution and the ferrimagnetic resonances staggered over the required frequency band. Finally, the theory is illustrated by the measurement of the backscattering losses of a v.h.f. ferrite-coated antenna in the microwave frequency band (for both TM and TE polarizations of the incident waves) and its radiation performance at the v.h.f. range View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Developments in frequency-response determination using Schroeder-phased harmonic signals

    Page(s): 226 - 232
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (714 KB)  

    A multi-frequency identification scheme employing Schroeder-specified relative phasing to achieve low-peakfactor excitation signals has been devised. These so-calledSchroeder-phased harmonic signals have been proposed as a convenient multi-frequency signal for frequencyresponse testing offering high-power with low peak-factor and a flexible choice of test spectrum. In this paper the use of these signals is extended to obtain frequencyresponse information from multi-variable and sampleddatasystems. Additionally there is a detailed discussion of the computational processes relevant to the use of these signals when the system output signals are contaminated significantly with noise. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Voiced/unvoiced band-switching system for transmission of 6 kHz speech over 3.4 kHz telephone channels

    Page(s): 233 - 235
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1622 KB)  

    A voiced/unvoiced band switching system is described for the transmission of wide bandwidth speech (here 300to 6000 Hz) over commercial telephone channels. Timewaveforms and spectrograms are presented to demonstrate that the 6 kHz speech can be compressed into a 3-4 kHz telephone channel and yield improved speech quality at the receiver compared to current telephone quality speech. Informal listening experiences confirm these results. The system is conceptually simple and inexpensive to implement. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Structured magnetic media for data security

    Page(s): 236 - 240
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1045 KB)  

    A method is described of structuring or `freezing¿ digital encoding into a magnetic tape so that it is permanent and non-erasable. It is then shown how normal or `soft¿ magnetic encoding can also be recorded on such a tape, and ensure the integrity of the normal encoding. It is further shown how structured tape may be fixed to the cards and documents to make them secure and machine readable. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some novel elements for delta-modulated signal processing

    Page(s): 241 - 250
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (886 KB)  

    New and interesting multipliers are proposed to use for the direct-multiplication of delta-modulated signals by constants. In addition to a non-recursive form, three recursive-form delta multipliers are given. The recursive multipliers are suitable for multiplication by periodic numbers or by non-periodic numbers which can be approached by periodic ones. A significantly smaller number of delta adders is needed for the realization of recursive delta multipliers, than for the non-recursive ones. In addition, an interconnecting method is suggested, if the outputs of the multipliers are to be added. With the method a significant reduction of the scaling-down is achieved as well as a reduction of the total number of the necessary adders for the realization of the multipliers. The combination of interconnecting multipliers and delta doubters gives very good results for the realization of digital filters. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Book review: Early Radio Wave Detectors

    Save to Project icon | PDF file iconPDF (130 KB)  
    Freely Available from IEEE