Propagation of ultra wide-band signals in lossy dispersive media

Development of a channel model for continuous frequencies enables the analysis of communications in an ultra wide band wireless network in indoor environment including a single transmitting and a single receiving antenna. In this work we will describe a model taking into account multiple reflections which are a consequence of the room in which both transmitter and receiver are localized including wall, ceiling and floor reflections. Moreover, our model enables the analysis of a communication channel between adjacent and distant rooms, in those cases we take into account the wide band signal propagation through separating walls. The model developed is in the frequency domain and thus allows analyzing dispersive effects in transmission and reflection of ultra short pulses in UWB communications from building materials which the room is made of in accordance with their complex dielectric coefficients. For this purpose a library of material characteristics of various materials (concrete, reinforced concrete, plaster, wood, blocks, glass, stone and more) in the standard frequency domain for wireless networks was assembled. One of the important phenomena for UWB communications which our research has revealed is the in-wall multiple reflections resulting in echoes of the narrow pulse transmitted. Our model takes into account antenna polarization and beam shape, the effect of those traits are clearly distinguishable. Space-frequency theory of the propagation of an ultra-wide band radiation in dielectric media is presented. The transfer function of a slab of material is derived in the frequency domain, considering polarization losses via a complex permittivity. It is shown that absorptive and dispersive effects play a role in the transmission and reflection coefficients of the electromagnetic incident field. The theory is applicable in the analysis of broadband communication links operating in wireless local or personal area networks. In an indoor scenario, the construction material of the walls attenuates the propagating waves in a dispersive manner, causing amplitude and phase distortions in the transmitted signal.