The ultra-wideband indoor radio channel: Antenna and propagation aspects

After some basic definitions regarding the ultrawideband radio channel, this paper illustrates the characteristic effects of varying the bandwidth on the channel impulse response ranging from narrowband to ultra-wideband. A coherent description of antenna transfer functions that are suited as building blocks for ultra-wideband channel models is reviewed and a coherent equivalent to Friis´ formula based thereon is given. Furthermore, the particular shape of the multipath envelope found in some ultra-wideband channels, which is different from a simple exponential decay, is discussed using the example of measured data.