Question

the directivity of an electric current element is

Answer 1

Directivity is a measure of the degree to which radiation emitted is concentrated in a single direction. It is measured for an antenna or for an optical system. The directivity of an antenna is the maximum value of its directive gain.
Peak directivity is simply the ratio of the power density of the antenna in the most concentrated direction and that pf a isotropic antenna.
Directivity is either expressed in algebraic numbers or in decibels (dB).

Answer 2

The directivity of a current element in a conductor, can be decided based on the charge of the majority charge carriers.

If the majority charge carriers are positive, the directivity of current element is the same as the direction of motion of the positive charges.

If the majority charge carriers are negative, the directivity of current element is opposite to the direction of motion of the negative charges.