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Mapping of radio-climatological parameters and their practical utility
Fišer, Ondřej ; Pek, Viktor ; Pitaš, Karel
Mapping of radioclimatological parameters in the form of digital or classic “paper“ maps is very useful for the planning of microwave satellite connections. Variables for simple calculation of water vapor attenuation (integrated water vapor content), clouding of cloud (integrated water content) and rainfall (precipitation intensity at 0.01%) are most often mapped. The formula for the distribution function of the attenuation is then relatively simple. Mapping is mostly done by ITU-R, ESA and WMCWF.
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Vertical rain profile to estimate satellite signal attenuation
Fišer, Ondřej ; Pek, Viktor ; Pitaš, Karel
With respect to the propagation of electromagnetic waves in frequency bands above 10 GHz, the attenuation due to the passage of electromagnetic wave hydrometers (rain, fog, snow etc.) must be respected in the design of analogue and digital satellite connections. The attenuation of the hydrometeorists depends on the length of the connection, transmission frequency, polarization and climatic conditions.
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Rain Data Analysis for cm and mm radiowave attenuation
Fišer, Ondřej
Rain is a random lossy dielectrics that is necessary to respect by the design of cm and mm links. The contribution deals with the physical (especially absorption and scattering) properties of rain drops. The inference of the formula for the specific rain attenuation is denoted. The main parameters and its statistical properties describing the rain volume are shown (it is,for instance, the rain rate and its cumulative distribution). The technique to measure the rain rate is discussed. The main goal of the contribution is the drop size distribution and its impact on the radio waves.
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Comparison of the rain rate measurements at different localities from the microwave attenuation viewpoint
Fišer, Ondřej
The rain rate distribution is the input data used in models predicting the rain attenuation distribution on microwave links. Some methods partially mitigating the rain attenuation are used in practice. The well known "site diversity" method is described in this contribution. The attenuation is obtained from the rain rates which are converted into the attenuation using the Assis-Einloft model. The rain rates are measured on 4 sites in the Czech Republic at distances from 8 to 150 km. It is shown that the site diversity gain is big (about 10 dB at 0.01% exceedance level at 12 GHz). The gain is increasing with the increasing distance (as expected) and is also a function of the azimuth of 2 sites. The north-south sites position has lower gain in comparison with the west-east position: it is due to the prevailing frontal motion from west to east in our country.
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First results of experimental investigation in frequency band 58 GHz
Kvičera, V. ; Grábner, M. ; Fišer, Ondřej
TESTCOM and Institute of Atmospheric Physics, ASCR launched a common experimental research in the frequency band 58 GHz on the experimental hop Geophysical Institute, ASCR - TESTCOM in the frequency band 58 GHz since December 2000. Our research has been focused on obtaining knowledge concerning attenuation due to hydrometeors in our specific climatic conditions. The path length is 846 m, used frequency is 57 650 MHz with V polarization. Records of received signal were statistical processed and cumulative distributions of attenuation due to hydrometeors for individual month as well as the first year period of observation from December 2000 to November 2001 were obtained. The records of attenuation were compared with the concurrent meteorological situation and attenuation due to rain, snow, fog, rain with snow and rain with hail were separatd. Rain intensities have been measured at both sites of path. Obtained CDs of rain intensities are presented.
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