In the context of human exposure to Radio Frequency (RF), measurements of electromagnetic fields are performed, according to standard measurement protocols, using isotropic broadband probes with or without service filters. Two electric field measurement probes are herein examined. Their responses to different typical WIMAX emissions are analysed. Results show that these probes are not accurate enough for the next generation OFDM (Orthogonal Frequency Division Multiplexing) communication systems. A new correction method for these probes is proposed for the evaluation of the RF exposure due to WIMAX systems.