I'm not entirely sure of your question, but I do know at radio and microwave frequencies there can be a phase shift between the current at the core and the conductor's skin. This is skin effect. This can introduce unwanted impedances with various consequences.
In radio, this is something very important to consider with circuit and antenna system design. For antennas, as an example, power loss by way of heat can attenuate a signal, especially with longer transmission lines. With circuit design, particularly at microwave frequencies, the slightest added resistance or reactance has to be accounted for.
This is why in both cases special care has to be taken in selecting the proper cables, wires, shielding, and mimimize excessive distance between components and equipment if possible.
I'm not sure if this is what you are asking, but I hope it helps.