Where would this be used? The EMCO 3109 is primarily used for Radiated Immunity testing to measure electric field emissions generated by the Equipment Under Test (EUT). It can be mounted on a tripod or stand for flexible test setups. EMCO model 3109 is designed to generate high levels of EM fields. Radiated Immunity as per EN61000-4-3 is achieved using the 3109 because of its ability to handle high power levels 1kW over a broadband. The unit uses a modified Guanella balun for impedance transformation and matching.