An ultra-wideband spatial filter for a tunnel environment

An ultra-wideband (UWB) spatial filter concept is proposed for one-dimensional time-of-arrival (TOA) localization in a tunnel environment. The spatial filter exploits the fact that electromagnetic waves travel as modes in a tunnel and that these modes can be filtered using a sparse array of antennas. It is shown that the spatial filter delivers centimeter ranging accuracy at moderate to high signal-to-noise ratio (SNR) values even when the tunnel is heavily overmoded. Results generated using an analytical equation model and ray tracing model are used to evaluate the performance of the spatial filter.