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.

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Wireless mobile ad-hoc networks (MANeT) provide hop-by-hop routes (e.g. 2.4 GHz ZigBee) along shortest paths to reach the controller from many sensor sources. An outdoor line-of-sight RF link can cover over 100 metres. However, inside a multi-storey building, the range often drops to less than 10 metres or is even completely blocked by floors and ceilings. The power-line network of a building can become an auxiliary signal transmission medium which would guide the weak signals from sensors at different locations to the base controller several storeys away.