General results obtained previously for slots of arbitrary shape are applied to the case of a transverse rectangular slot in a circular cylinder. It is shown that the principal transverse plane pattern of such a slot in which the excitation has only a circumferential tangential electric field component is the same as the pattern generated by an infinite axial slot with the same circumferential excitation. Theoretical and experimental curves are given for the narrow‐width half‐wave‐length slot.