Path-loss exponents of ultra wideband signals in line-of-sight environments

The paper proposes a new ultra wideband (UWB) line-of-sight path loss formula based on the narrowband two-path (direct and ground reflected waves) model, taking into account the bandwidth of signals. The following results were derived from numerical calculations: (1) UWB signals suffer less interference fading than narrowband signals; (2) UWB path loss exponents change approximately to 2 to 4 around the breakpoint; (3) the breakpoint distance depends on the transmitting and receiving antenna heights, the lowest frequency, and the bandwidth of the signal. Indoor experimental results verified the validity of this new formula.