On the mathematical modelling and spatial distribution of UWB frequency dependency

Increasing the instantaneous bandwidth of wireless transmission pose new challenges to the design of communication devices. Apart from observing notches in the frequency domain, ultra wideband (UWB) signals also suffer from spatial variations in power, as a function of frequency, which are known as frequency dependent path-loss. To have more insight into this problem, we have conducted fundamental tests in an anechoic chamber. For the experiments, a metallic cylinder scatters UWB test signals radiated by a biconical antenna. A similar antenna, which an accurate servo-positioner relocates, collects the resulting signals for analysis. We then derive a mathematical equivalent of the experiments and use the positioning information to compare predicted and measured data. Spatial analysis of the results show that small scattering objects induce frequency dependent responses, which occur over distances in the order of centimetres. Thus, identifying important aspects for future consideration.