Electromagnetic Spectrum

The Electromagnetic Spectrum is all possible frequencies of electromagnetic radiation, 0 Hz (DC) to infinity. Various frequency ranges are referred to as radio, microwave, terahertz, infrared, visible, ultraviolet, X-ray and gamma ray. I show one breakdown of the spectrum below, but the naming convention is not uniform.

• There are defined radio bands from 3Hz to 300GHz, the areas I show as electric, radio, and microwave.
• Frequencies from 3Hz to 3kHz, which I show as electric, are used for undersea communication rather than atmospheric transmission and are often excluded from the radio band.
• The radio band is sometimes defined as 3kHz to 300GHz, the areas I show as radio and microwave.
• The microwave band is sometimes defined as 3GHz to 3,000GHz, the areas I show as microwave and terahertz.
• Until recently, the terahertz band, 300Ghz to 3,000GHz, has been of little interest because it is highly absorbed by the Earth's atmosphere and radio waves of these frequencies were challenging to produce.

RFID uses the bands I show as radio (primarily) and microwave.

Image credit: Bill Wilkinson