This Technical Report addresses exposure evaluation techniques for the overall exposure level caused by the simultaneous exposure to multiple narrowband EM sources. Throughout the Report, it is assumed that the exposure evaluation occurs under static conditions, i.e., the source position and transmit-mode characteristics (e.g. emitted power, modulation scheme, etc.) of the device(s) under test do not vary significantly over the time required to carry out the evaluation using the chosen evaluation technique (e.g., field measurements). The vast majority of wireless communication systems world wide employ signalling schemes featuring narrowband waveforms, here