Analysis of Propagation Characteristics for Various Subway Tunnel Scenarios at 28 GHz

Table 2

Material property parameters after calibration.

	Material	Frequency (GHz)	Relative permittivity	Conductivity (S/m)	Thickness (m)	Roughness (m)
Tunnel wall	Concrete	28	5.31	0.48	0.5	0.005
Rail	Metal 1	28	—	—	0.05	0.0001