PRODYN's precision high frequency ground plane electric field sensors are designed to measure time rate-of-change of electric displacement over a wide frequency spectrum. They can also be used to measure the time rate-of-change of surface current density. Surface (radial) or thru-the-ground plane (axial) output configurations are available to allow testing flexibility.  These sensors have a single 50 Ohm output connector, so no BALUN is required.  The output still requires integration to determine the field strength.