Summary form only given, as follows. The comments of Prof. Delogne on our paper ("Calculated channel characteristics of a braided coaxial cable in a mine tunnel") seem very appropriate and instructive. I do agree with Prof. Delogne that at low frequencies, questions related to the receiver noise and perhaps the receiver matching become of primary importance. The coupling loss in the aforementioned paper is actually related only to the mutual impedance between the transmitting and receiving antennas but does not include the input resistances of these antennas. This drawback has been repaired in the paper "Calculated transmission loss for a leaky feeder communication systems in a circular tunnel" by Hill and Wait (1976). However, by limiting the antenna input resistance to a certain minimum value at the lower frequencies, the two definitions of the coupling loss in our papers become identical (within a constant). It is interesting to notice that both papers confirm the result that the coupling loss is a very slowly varying function of frequency for frequencies less than about 35 MHz. This is so in spite of the different approaches used in the two papers. Specifically, the coupling loss in Mahmoud and Wait's paper is obtained without assigning any particular location or orientation of the antennas; hence, it can be considered as some kind of average coupling loss over various locations and orientations.

The braided coaxial cable is studied as a communication scheme in a mine tunnel. A simplified rectangular waveguide model is adopted for the tunnel, and the shield of the cable is assumed to behave as a single inductive transfer impedance. Specific results on the attenuation of the monofilar and bifilar (or coaxial) modes of propagation, taking into account the possible existence of a thin lossy film on the cable, are presented. In order to estimate the maximum possible range of communication, we consider the coupling factors of these modes to transmitting and receiving dipoles inside the tunnel, and we present results on these factors for various cable parameters and over a wide range of frequencies.

We obtain numerical results of the attenuation and phase constants of the lowest order modes in a rectangular tunnel with an axial wire for various values of physical parameters that are important in intramine communications and remote control. Besides the perturbed free modes of the empty guide, a TEM-like mode, which is highly influenced by the wire impedance and location, is identified. Also the excitation mechanisms of the modes are considered from the standpoint of point-to-point communication within a mine tunnel.