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This paper presents an empirical model for the statistical prediction of site diversity gain on earth space propagation paths. A modelling approach is described which incorporates 46 months of Nimrod rain radar data recorded in South England. The dual site diversity (SD) gain is developed as a function of several parameters, including time percentage of average year, site separation, baseline orientation, link frequency and path elevation angle. The model performs with an overall root mean square error of 1.87 dB computed over a wide variety of link configurations with elevation angles ranging from 10^\circ to 50^\circ and transmission frequencies from 16 to 50 GHz. The performance of the new model is checked against satellite beacon measurements as well as the empirical and physical models recommended by ITU-R. [ABSTRACT FROM PUBLISHER]

A wide-slot UWB antenna is presented for intended use in the detection scheme being developed at the University of Bristol, based on the principle of synthetically focused UWB radar using a fully populated static array. The antenna's measured and simulated, input and radiation characteristics are presented and compared to an existing, stacked patch antenna that has been designed for the same purpose. The results of this study show that the wide-slot antenna has excellent performance across the required frequency range. Compared to the stacked-patch antenna used in our previous array, the wide-slot antenna can be 3 times smaller (in terms of front surface). The compact nature of the slot antenna means that the detection array can be densely populated. Additionally, this new antenna offers better radiation coverage of the breast. For angles up to 60° away from bore-sight radiated pulses are almost identical (fidelity >95%), whereas for the patch antenna fidelity falls to 58% at the angular extremes. This uniform radiation into the breast should result in focused images with low levels of clutter. [ABSTRACT FROM AUTHOR]