Impedance analysis of dipoles in circular tunnel with braided coaxial cable

To analyze the impedance of the dipole in tunnel, the electromagnetic fields of the diplole with braided coaxial cable in a circular tunnel are formulated and the expression for the impedance of the dipole is deduced by the method of EMF. The numerical results are given. The main conclusions are as follows: if the distance between the tunnel and the braided cable is closer, the resistance of the dipole is greater; the presence of the braided cable increases the resistance for both a transversely oriented electric dipole and a circumferentially oriented magnetic dipole, but don't affect the resistance for both a circumferentially oriented electric dipole and a transversely oriented magnetic dipole.