Wideband radio channel measurements for train tunnels

We present and analyse the results of wideband radio channel measurements performed in tunnels. Both a high speed train tunnel and a smaller test tunnel have been investigated with both antennas and leaky feeders as fixed radiators. The results show typical features of the tunnel radio channel with typically low delay spread combined to significant slow fading of the LOS signal due to interferences. The delay spread may increase substantially during the fading dips.