EM wave propagation on the surface of human body

The signal transmission mechanism for human body channel has been described by the propagation of electric field on the surface of human body from an electrical dipole source [1]. 

The electric field received from an infinitesimal dipole in free space is given by the following equation, [1]

Where, I is the current in amps, dl is the length of dipole in meters, k is the wave number, ω is the angular frequency in radians per second and ε0 is the permittivity of free space. The term 1/r refers to far-field, 1/r² refers to induction field and 1/r³ refers to near-field of the dipole.

If we assume that the electromagnetic wave propagation theory as depicted by the above equation correctly explains the phenmenon of signal transmission on the surface of human body then how the following contradictions could be explained?

1. The relative permittivity for human body is aproximately 50 times more than in free space. If εr term comes in the denominator then the above electric field equation suggests 50 times weaker electric field propagation inside human body than free space. This is contradictory to the fact where conductive property of human body is described as a more suitable medium than free space for electric field propagation over a larger distance.
   
   
2. The above equation also suggests that the length of the electrical dipole decreases with increasing frequency. For a frequency of few MHz, the theoretical length or dimension of the dipole suggested by this equation is much greater than the practical electrical dipole which is actually used in the human body channel experiments in different research papers, which is again a contradiction.

References

[1] J.Bae, H. Cho, K. Song, H. Lee, and H.-J.Yoo, “The Signal Transmission Mechanism on the Surface of Human Body for Body Channel Communication,” IEEE Trans. Microw. Theory Tech., vol. 60, No. 3, pp. 582-593, March 2012