High elevation angle satellite‐to‐earth 12 GHz propagation measurements in the tropics

Abstract

SUMMARYA simple, low-cost propagation terminal for measuring path attenuation and site diversity, using satellite transmissions at 12 GHz, is described. The novelty of this system is the use of a standard domestic satellite low-noise block (LNB) front-end connected directly to a spectrum analyser in place of an expensive beacon receiver. A description of the equipment, an analysis of relevant system parameters, and a discussion of the environmental conditions are presented. The method used to obtain a clear-sky baseline reference and a description of the channel signal processing are given. Analysis of the rainfall rate and attenuation exceedances statistics has led to the proposal of a new model to derive the e!ective rain-cell diameters and e!ective rain-column heights in tropical areas for attenuation predictions in satellite communication link budget calculations. Site-diversity statistics are also examined. Though the main site is only 6.5 km inland from the second coastal site, there are marked di!erences in their rain-cell characteristics. The signi"cance of volume saturation of rain cells on modelling, the operating margins of the measuring system, and the relevance of the site-diversity data to enhancing the understanding of the proposed volume saturation model are discussed.

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

“…Rain attenuation may become very severe even for Ku-band radio waves in heavy rain regions like the tropics (Pan et al 2001, Pan andAllnutt 2004). However, demand for satellite communications is recently increasing in new developing areas such as the South-East Asia, which is one of the heaviest rain regions in the world .…”

Equatorial Rainfall Measurement on Ku-Band Satellite Communication Downlink

“…The probability of occurrence values for rain attenuation was greater than the rain rate for both the seasons. This is because the frequency of rain in the slant path is higher than the rain measured at site, a point [7]. The maximum rain attenuation and rain rate recorded were 38 dB and 230 mm/h.…”

“…For such a system the yearly rain rate statistics must be obtained for every location where a communication link is planned [4]. The effect of rain attenuation on communication systems has been of interest to many researchers but limited investigations in the tropics have been reported [9,7]. The lack of data for both rain rate and rain attenuation has lead to noticeable deviation of the prediction models for these regions.…”

Rain Attenuation Predictions at Ku-Band in South East Asia Countries

“…As the rain rate increases, reaching a maximum of 10 km while the rain cell diameter continue to decrease. Therefore, the proportional increase of rain volume, which is a function of rain rate, rain cell diameter and rain column height, would be saturating [7,15].…”

“…The precipitation observed over the globe often are a combination of the two rather than simply one or the other, however, the frequency of a particular rain structure may dominate a region [14]. In temperate climates, due to the large rain cell diameter, the attenuation increases with decrease in the elevation angle, however in the tropics, for the same rain rate, the converse is found to be true [15].…”