Transfer Lead Vector between Two Dipoles

Equation (6.15) gave the potential difference from a current carrying technically ideal dipole. Technically ideal CC dipole is explained in Section 6.2.3. Putting m = IL/c we have  

It is clear from this equation that it does not matter which dipole is CC and which is PU, in accordance with the principle of reciprocity. We separate the part of Eq. (6.29) associated with the PU dipole and call it the lead vector H  

The lead vector defines a transfer factor between the CC and PU dipoles. It depends on the resistivity p of the medium, the distance r between the dipoles, and the PU dipole length vector Lp . The scalar signal u created by a current dipole m = ILcc is  

Vector H has a free starting point but fixed magnitude and direction according to Eq. (6.30). The current dipole m is bound, but may vary in current I and length Lee- 

Lpu Lee [ 1] (technically ideal CC dipole far away from the PU dipole) 

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