12 Types of Radio Waves

John Spacey, March 09, 2021

Radio waves are wavelengths of electromagnetic radiation in the range 1 millimeter to 100,000 kilometers. All electromagnetic radiation with a wavelength longer than infrared light is considered a radio wave. Radio waves are naturally present in the solar system and on Planet Earth. They are also commonly used by technologies to transmit information. The following are common types of radio wave with examples.

Band	Frequency	Wavelength	Examples
Extremely Low Frequency (ELF)	3 to 30 Hz	10,000 to 100,000 km	Lightning, Earth's magnetic field
Super Low Frequency (SLF)	30 to 300 Hz	1,000 to 10,000 km	AC power grids
Ultra Low Frequency (ULF)	300 to 3,000 Hz	100 to 1,000 km	Submarine communication
Very Low Frequency (VLF)	3 to 30 kHz	10 to 100 km	Marine navigation, time signals, heart rate monitors
Low Frequency (LF)	30 to 300 kHz	1 to 10 km	RFID, amateur radio, AM longwave broadcasting
Medium Frequency (MF)	300 to 3,000 kHz	100 to 1,000 meters	AM radio, amateur radio, avalanche beacons
High Frequency (HF)	3 to 30 MHz	10 to 100 meters	Shortwave broadcasts, citizens band radio, amateur radio, RFID, radar
Very High Frequency (VHF)	30 to 300 MHz	1 to 10 meters	FM Radio, television broadcasts, aircraft communications, mobile communications, weather radio
Ultra High Frequency (UHF)	300 to 3,000 MHz	10 to 100 centimeters	Television broadcasts, microwave ovens, microwave communications, radio astronomy, mobile phones, WiFi, Bluetooth, GPS, FRS radios, GMRS radios, amateur radio, satellite radio, remote control systems
Super High Frequency (SHF)	3 to 30 GHz	10 to 100 millimeters	Radio astronomy, microwave communications, WiFi, modern radar, communications satellites, satellite television, satellite radio, 5G mobile
Extremely High Frequency (EHF)	30 to 300 GHz	1 to 10 millimeters	Microwave remote sensing, WiFi
Tremendously High Frequency (THF)	300 to 3,000 GHz	0.1 to 1 millimeter	Experimental medical imaging to replace X-rays, spectroscopy, remote sensing

In general, lower frequencies have better range but have less data capacity.

Although terms like "Tremendously High Frequency" sound quite dramatic, regular visible light is far higher frequency. Tremendously High Frequency is up to 3 THz and the frequency of visible light is about 400 to 790 THz. For this reason, the theoretical bandwidth capacity of fibre optics is far greater than any radio band used for wireless communications.

Ionizing radiation is far higher frequency than visible light or radio waves. For example, x-rays are 30 petahertz (PHz) to 30 exahertz (EHz).

Frequencies vs Wavelength

A frequency indicates how often waves repeat. This is measured in hertz such as Hz, kHz, MHz, GHz and THz. A wavelength indicates the length of each wave. This is measured with metric lengths such as millimeter, meter and kilometer. There is a relationship between frequencies and wavelengths as follows.

Frequency	Wavelength
1 Hz	299792.5 Kilometers
1 kHz	299.8 Kilometers
1 MHz	299.8 Meters
1 GHz	299.8 Millimeters
1 THz	299.8 Micrometers

The table above is rounded to one decimal place.

Frequencies

A hertz represents one cycle per second. This varies by wavelength and the speed of electromagnetic radiation. In a vacuum, electromagnetic radiation moves at the speed of light. The following units are used to represent hertz.

Unit	Cycles Per Second
Hertz (Hz)	1
Kilohertz (kHz)	1,000
Megahertz (MHz)	1,000,000
Gigahertz (GHz)	1,000,000,000
Terahertz (THz)	1,000,000,000,000
Petahertz (PHz)	1,000,000,000,000,000
Exahertz (EHz)	1,000,000,000,000,000,000

The cycles per second of a frequency is directly related to how much information can be sent on that frequency. For example, you can send more information on a 1 GHz frequency that an 1 MHz frequency.

Allocations

Each nation regulates the use of radio waves by dividing the radio spectrum into regions that are assigned to a purpose or entity. This is unbelievably complex as these aren't standardized from one country to the next and can change with time.