# Tenth International Conference on Antennas and Propagation (Conf. Publ. No. 436)

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Displaying Results 1 - 25 of 93
• ### Wideband characterisation and modelling of the mobile satellite propagation channel at L- and S-bands

Publication Year: 1997, Page(s):39 - 43 vol.2
Cited by:  Papers (2)
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The effects of the wideband propagation channel are critical in the design of mobile satellite systems (MSS), providing world-wide voice and data communications requiring higher data rates and quality of service. The variational effects of the narrowband propagation channel with respect to the elevation angle have been widely reported and modelled. However, there is very little data on the effects... View full abstract»

• ### Transmission of high power 9 MHz signals near ionospheric cut-off from SURA' towards the Moon and reception of the echo with the radio telescope UTR2'

Publication Year: 1997, Page(s):35 - 38 vol.2
| | PDF (480 KB)

Two unique broadband decametric arrays SURA and UTR2 are described in outline format. They are used for radio astronomy and radiophysical research (solar system investigations, ionospheric research, near-Earth plasma, etc). Both facilities were used in a `bistatic' configuration, transmitting from SURA and receiving with UTR2. The Moon and Sun were used as targets, NASA's WIND spacecraft was used ... View full abstract»

• ### Wideband limitations of ray-optical techniques in radiowave propagation prediction

Publication Year: 1997, Page(s):79 - 82 vol.2
| | PDF (468 KB)

Further growth of mobile communication systems and the provision of mobile multimedia services can only be achieved in the future through the use of sophisticated access schemes, some of which require wideband radio channel information for their planning (e.g. wideband DS-CDMA). The planning and deployment of spectrally efficient wideband wireless personal communication systems in turn requires a ... View full abstract»

• ### Multipath occurrence identification technique on terrestrial LOS radio links

Publication Year: 1997, Page(s):381 - 382 vol.2
| | PDF (132 KB)

The line of sight (LOS) radio links network have to be designed to meet very high quality objectives. The planning involves careful consideration of the actual path and the propagation effects. A precise prediction of the expected multipath fading is therefore important. There is no previous radio measurements on multipath activity in the hilly region of Cluj county, so little information is avail... View full abstract»

• ### Transionospheric propagation at the boundary of radio transparency range: results of Russian space experiments and plans for low orbiting pilot space station

Publication Year: 1997, Page(s):31 - 34 vol.2
| | PDF (336 KB)

To ensure good design, as well as reliable and stable operation of radio systems using radio communication channels, it is essential to determine the ionospheric spatial structure. Installation of the ionosonde on-board the satellite provided the optimum possibility for determining the ionosphere spatial structure. The ionosonde emits radio waves that propagate throughout the ionosphere and allows... View full abstract»

• ### The effects of antennas on HF propagation level

Publication Year: 1997, Page(s):75 - 78 vol.2
| | PDF (444 KB)

The transmitting antenna for HF communication links is generally simple with a vertical or horizontal polarization. The receiving antenna provides signals corresponding to different paths or modes( O and X). To interpret HF communication attenuation, fading is computed using a statistical method and the classical antenna field pattern. Such a radiation pattern is inadequate in the case of HF propa... View full abstract»

• ### Dual polarised propagation channel: theoretical model and experimental results

Publication Year: 1997, Page(s):363 - 366 vol.2
Cited by:  Papers (2)  |  Patents (2)
| | PDF (312 KB)

The development of radio relay systems with frequency re-use of orthogonal polarisations has requested the extension of the existing propagation channel models in order to take into account the transmission characteristics of the atmosphere in both polarisation planes. A general approach has been developed in order to characterize this particular propagation channel considering every possible rele... View full abstract»

• ### Millimetre wave propagation: a measurement expert system for the millimetre wave propagation modelling validation

Publication Year: 1997, Page(s):243 - 246 vol.2
Cited by:  Papers (3)
| | PDF (332 KB)

A modern innovative measurement system is presented. The system allows for the measurement of millimetre wave propagation in urban and sub-urban areas. The system was expressly designed to allow easy propagation modelling. These features were obtained by acquisition in a georeferred basis of measured data in order to facilitate their comparison with prediction results. The measurement system will ... View full abstract»

• ### Measurements of non line-of-sight VHF propagation over the sea surface

Publication Year: 1997, Page(s):378 - 380 vol.2
Cited by:  Papers (1)
| | PDF (216 KB)

On two occasions in 1994, a set of trials were carried out to measure the signal strength as a function of the range between three vertically-polarised floating transmitters, operating at frequencies in the VHF band, and a ship-mounted receiver. The trials corresponded to sea states from 2 to 5, and ranges up to 30 Nautical miles (1 Nm=1852 m), beyond line of sight of the transmitter. The paper de... View full abstract»

• ### Neural networks in ionospheric prediction and short-term forecasting

Publication Year: 1997, Page(s):27 - 30 vol.2
Cited by:  Papers (2)
| | PDF (368 KB)

This paper discusses appropriateness of the neural network approach for ionospheric prediction and short-term forecasting. The idea of using the neural network technique to predict the future behaviour of a time series of the vertical-incidence ionospheric data has been presented and endorsed in the framework of the COST 251 project. It is based on the well-known fact that in recent years attentio... View full abstract»

• ### Some super-resolution DF measurements within the HF band

Publication Year: 1997, Page(s):71 - 74 vol.2
| | PDF (384 KB)

The unknown propagation mode content of signals monitored in some earlier super-resolution HF-DF experiments was a significant limitation in the interpretation of the measurements and inferences concerning the mode content had to be made from the processed data. In order to overcome this limitation, further experiments have been undertaken in which the propagation mode content of the signals was d... View full abstract»

• ### Analysis of mobile-satellite propagation measurements at 18.7 GHz: vegetation effects

Publication Year: 1997, Page(s):9 - 14 vol.2
Cited by:  Papers (2)
| | PDF (468 KB)

Some measurements in the Ka band (at 18.7 GHz) on a land mobile satellite propagation link (ITALSAT 13.2° EST) have been analyzed. These measurements have been performed in surrounding areas of Turin, in the period between February and December 1995, Italy, using the ESA Land Mobile Beacon Terminal (LMBT). ITALSAT is seen from Turin with an elevation angle of 38.7° and an azimuth angle of ... View full abstract»

• ### Mapping of radiosonde-derived clear air climatic parameters using neural modelling techniques

Publication Year: 1997, Page(s):329 - 333 vol.2
Cited by:  Papers (1)
| | PDF (684 KB)

This article is concerned with the study of climatic ducting statistics based on the analysis of radiosonde data, the aim being to characterise the effects of climate in statistical propagation prediction models. Discussed are issues of data acquisition, processing and validation, and analysis of derived ducting statistics. Examples of regional and global maps of these statistics are also provided... View full abstract»

• ### Diffraction of an electromagnetic wave on a flat periodic structure

Publication Year: 1997, Page(s):239 - 242 vol.2
| | PDF (268 KB)

The authors use a flat periodic structure to represent a half-infinite dielectric layer with complex dielectric permeability on which are located metal bars. EM diffraction by this system and losses are discussed View full abstract»

• ### Radar-derived path reduction factors for terrestrial systems

Publication Year: 1997, Page(s):218 - 221 vol.2
Cited by:  Papers (4)
| | PDF (304 KB)

Attenuation due to rain becomes an increasingly important factor as frequency increases above 5 GHz. For terrestrial links operating at high microwave and millimetre wave frequencies, it is considered to be the dominant mechanism affecting system availability. At frequencies above 30 GHz, cloud and fog will also become a significant factor, while in high latitude regions, or high altitude location... View full abstract»

• ### Modelling of land mobile satellite channels based on measurements at 13° and 29° elevation angle

Publication Year: 1997, Page(s):54 - 58 vol.2
Cited by:  Papers (2)
| | PDF (396 KB)

This paper presents results from land mobile propagation measurements conducted by Inmarsat at 13° and 29° elevation angles in the UK. A number of simultaneous recordings have been made at L-band, using both directive and omnidirectional antennas. The measurements took place in the suburbs of London in a variety of propagation environments ranging from open to shadowed areas. Furthermore, ... View full abstract»

• ### Tenth International Conference On Antermas And Propagation

Publication Year: 1997, Page(s):i - xxviii
| | PDF (1140 KB)

First Page of the Article
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• ### A model of UHF propagation in urban environment

Publication Year: 1997, Page(s):94 - 97 vol.2
| | PDF (280 KB)

The introduction of cellular mobile telephones and other communications systems in the UHF band (300 MHz-3 GHz) has imposed the need to predict radio path loss in urban environment between an elevated antenna and mobiles at street level. Response to this need has generally been the development of empirical prediction models based on collected measurements of received signal strength. Measurements ... View full abstract»

• ### Performance characterisation of millimetre wave mobile radio systems in forests

Publication Year: 1997, Page(s):391 - 396 vol.2
Cited by:  Papers (1)
| | PDF (356 KB)

The frequencies in the oxygen absorption band in the region of 60 GHz have been suggested for urban microcellular communications. This is due to the extra attenuation exhibited by the atmosphere in this frequency region, thus allowing for greater frequency re-use to be employed. Multipath in a microcellular forest environment due to reflections and scatter off foliage, with line-of-sight (LOS) pre... View full abstract»

• ### The statistics of propagation on the 500 m millimetre wave experiment at Chilbolton

Publication Year: 1997, Page(s):374 - 377 vol.2
Cited by:  Papers (1)
| | PDF (340 KB)

The rapid and continuing expansion in communications is imposing ever-increasing demands on the electromagnetic spectrum, which, although a reusable resource, is becoming over populated, giving rise to additional problems such as interference between adjacent channels and restricted bandwidth (and therefore channel capacity). There is a need to develop communications systems to higher frequencies,... View full abstract»

• ### Determination of HF ray path parameters using a multi-quasiparabolic model ionosphere

Publication Year: 1997, Page(s):23 - 26 vol.2
| | PDF (312 KB)

The multi-quasiparabolic (QP) model ionosphere has become available with the desirable features of providing explicit oblique ray path analytic expressions for ground range, reflection height and phase path, etc. at HF radio frequencies. The need for time-consuming numeric ray tracing is reduced. Electron density profiles are synthesised as combinations of QP and inverted QP segments to provide a ... View full abstract»

• ### Some observations of the directions of arrival of the Doppler components of an ionospherically reflected HF radio signal from Svalbard to the UK

Publication Year: 1997, Page(s):67 - 70 vol.2
| | PDF (340 KB)

Observations of the direction of arrival of a narrow band pulsed channel sounding signal propagated over a high latitude path have been made with a multichannel receiver system connected to a wide aperture antenna array. The signals received on each antenna were processed to provide a measure of the relative times of flight of the propagating modes and their associated Doppler spectra. In this way... View full abstract»

• ### Vegetation attenuation: modelling and measurements at millimetric frequencies

Publication Year: 1997, Page(s):5 - 8 vol.2
Cited by:  Papers (14)
| | PDF (388 KB)

Several measurements have been made to determine the extent of attenuation of millimetre-wave signals when propagated through vegetation. Methods for predicting such attenuation exist, but are either deterministic in form and therefore complex to implement completely empirical and take no account measurement geometry. A new semi-empirical model is presented which is based on measurements of vegeta... View full abstract»

• ### Remote sensing of radio refractivity by lidar

Publication Year: 1997, Page(s):325 - 328 vol.2
| | PDF (348 KB)

Deterministic modelling of tropospheric radio propagation and exploitation of variations of microwave radar propagation require high quality, high resolution refractivity profiles in the first 1-2 km above the Earth's surface. Currently, routine measurements of refractivity are based on radiosonde measurements (via in-situ measurement of temperature and water vapour). Unfortunately, radiosondes ha... View full abstract»

• ### Ray tracing and imaging techniques in urban pico and micro cell wave propagation modelling

Publication Year: 1997, Page(s):311 - 315 vol.2
Cited by:  Papers (2)
| | PDF (524 KB)

Cellular networks show a steadily increasing number of subscribers. During “rush hours” high blocking rates have already been observed in densely populated regions. To increase the network's capacity in such areas, base stations with antennas below roof-top level and limited cell radii are used. For these urban pico or micro cells wave propagation effects along street canyons are often... View full abstract»