Electromagnetic waves with radio frequencies (RF) are part of the non-ionizing electromagnetic spectrum in the range 10kHz - 300GHz (although different sources vary in this range definition). In our ECI we involve also extremely low frequency (30Hz - 10kHz).
These RF waves are also called electromagnetic radiation or radiation.
Electromagnetic Radiation is emitted in discrete units called photons and has at the same time properties of waves. It travels through space at the speed of light.
Radiation has an electro and a magnetic field component. This forms a so called electromagnetic field (EMF). A Radiofrequency electromagnetic field (RF EMF) is a field of a wave in the radio spectrum.
When we measure the "strength" of those fields, we measure power density expressed in W/m2 (Watt per square meter).