IEE Colloquium on HF Antennas and Propagation

14-14 Nov. 1995

Filter Results

Displaying Results 1 - 10 of 10
  • Analysis and measurement of the 'Hartley effect' in HF curtain arrays

    Publication Year: 1995, Page(s):1/1 - 1/7
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (378 KB)

    This paper describes a method for predicting the operating performance of an array (input match, power split between the stacks and the voltages on components) based on a 4-port S-parameter measurement and on a model of the array's bay feeder network. The measured S-parameters are converted to an admittance matrix (Y-parameters) and used to terminate an equivalent circuit of the array's bay feeder... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Predicted and measured patterns of vehicle-mounted whip and loop antennas for near vertical incidence skywave (NVIS) propagation

    Publication Year: 1995, Page(s):2/1 - 2/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (365 KB)

    We have combined the relatively mature numerical technique of the moment method computer modelling with a powerful, though less well-known, method of antenna synthesis which is based on the procedure of characteristic modes (CM), to both analyse and then to design optimum antenna systems for vehicular NVIS applications. Regardless of the maturity of an analytical technique however, the acid test o... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of phase errors on the accuracy of MUSIC

    Publication Year: 1995, Page(s):3/1 - 3/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (408 KB)

    Expressions are obtained for the measurement variance, for both azimuth and elevation, in terms of the phase error variance and the array geometry, using MUSIC as the DF processing method. MUSIC is a widely known superresolution method, often used as a standard for comparison with other methods. Although the results are derived for MUSIC they are likely to be a good indication of the performance o... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Super-resolution HF DF measurements with simultaneous chirp sounding for a path within the UK

    Publication Year: 1995, Page(s):4/1 - 4/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (524 KB)

    In order to better understand the behaviour of several super-resolution direction finding (DF) algorithms under various propagation conditions, measurements are being made over a path within the UK for which chirp sounding measurements are also being undertaken. The DF measurements have been made using a multichannel receiver connected to several wide aperture antenna arrays. Several interesting o... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Neural network beamformer for narrow-band HF transmission

    Publication Year: 1995, Page(s):5/1 - 5/8
    Cited by:  Papers (1)  |  Patents (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (485 KB)

    The multi-layer perceptron (MLP), an artificial neural network, is applied to adaptive beamforming over narrow-band HF channels. An HF data transmission system is simulated, incorporating QPSK modulation, demodulation, space diversity channel model and adaptive beamforming. The simulated diversity channels are characterised by Rayleigh fading and have time-varying characteristics. MLP beamformer h... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • OFDM design considerations using the HF fading channel

    Publication Year: 1995, Page(s):6/1 - 6/4
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (249 KB)

    Investigates the design parameters of an orthogonal frequency division multiplexed (OFDM) signal and relates these to the transmission characteristics of the HF ionospheric channel. OFDM is essentially a parallel modem technique where a number of carriers are transmitted and phase modulated each with a low symbol rate. Similar systems have been used at HF for some years. Carriers are orthogonally ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Review of COST 238 (PRIME) achievements

    Publication Year: 1995, Page(s):7/1 - 7/6
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (472 KB)

    COST 238 (prediction and retrospective ionospheric modelling over Europe-PRIME) was a four-year project sponsored by the European Commission initiated in March 1991 and involving some 72 research workers from 31 organisations in 17 countries. The objectives, embodied in the agreed Memorandum of Understanding were: "to develop techniques for using ionospheric sounding information taken from existin... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A HF ionospheric propagation model using analytic ray tracing

    Publication Year: 1995, Page(s):8/1 - 8/6
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (445 KB)

    A method to approximate horizontal gradients when using analytic ray tracing is presented. This method involves automatically tilting the modelled ionospheric profile by displacing the Earth's centre. This method is applied to a grid point ionospheric model which consists of a known ionospheric model coupled with real-time ionospheric measurements at a number of locations. Thus, the grid point ion... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • HF scatter from artificial irregularities above Tromso

    Publication Year: 1995, Page(s):9/1 - 9/7
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (408 KB)

    The paper summarises some observations of backscatter from artificial irregularities produced by the Tromso heater. The observations were carried out with the newly constructed CUTLASS radar which is located in Finland. A second stage of the CUTLASS system is under construction in Iceland. CUTLASS is an HF phased array radar operating at frequencies between 8 and 20 MHz and is capable of electroni... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A BLOS-HF decision aid

    Publication Year: 1995, Page(s):10/1 - 10/5
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (432 KB)

    A decision aid used to calculate signal coverage areas and signal interference regions in beyond line of sight (BLOS) high frequency (HF) communications systems is described. The interference and coverage capabilities of HF-BLOS communications systems are influenced by the ionospheric environment through which radio signals must propagate. A technique based on the tactical use of signal propagatio... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.