Radio signals are sent via radio waves, which are a form of electromagnetic energy or radiation.
Recall that a radio wave consists of both electric and magnetic fields oscillating at right angles to each other.
Combining electrical and magnetic gives us the term electromagnetic.
Like all waves, radio waves vibrate or oscillate at a specific rate or frequency.
This vibration frequency is normally measured in cycles per second and its units are Hertz. Rates of oscillation in radio work are thousands and millions of Hertz (Hz). With standardized metric prefixes for SI units , this means practical radio frequencies are in kHz, MHz, and GHz.
The common and familiar term RF is short for radio frequency. It’s really an adjective, not a noun. While we may say just RF (“You have a big RF leak, there, Fred”), we really mean radio frequency energy or signals. RF is not a thing in and of itself.
So what is a radio frequency , then? They are a large chunk of frequencies in the middle of the electromagnetic spectrum (the range of possible frequencies from 0 to measurably high). Technically radio frequencies start at low audio frequencies and run up to just below infrared light, basically 30Hz-300GHz. Different sources specify other upper/lower boundaries because a more practical range is the low frequency band up through microwaves. However you define it, this range of frequencies is known as the radio spectrum.
We will follow up with detailed posts on the important topics of RF wavelength and amateur radio bands, along with RF safety. Coming soon to Newhams.info; stay tuned.