A radio frequency sensor assembly includes a sensor casing disposed around a central hole, the sensor casing including a first conductive cover and a second conductive cover. The assembly includes a cavity disposed around the central hole and includes a dielectric material, the cavity being bounded by a first major outer surface and a second major outer surface along a radial direction from a center of the central hole, where the first conductive cover is electrically coupled to the second conductive cover through a coupling region beyond the second major outer surface of the cavity, and electrically insulated from the second conductive cover by the cavity and the central hole. The assembly includes a current sensor electrically insulated from the sensor casing and including a current pickup disposed symmetrically around the central hole, the current pickup being disposed within the cavity and being insulated from the sensor casing.