Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
HF
References
Images
Diagram illustrating the commercially used bands of the radio-frequency spectrum, with labeled sections for VLF, LF, MF, HF, VHF, UHF, SHF, and EHF. Each band shows example uses such as maritime radio, AM/FM radio, television, mobile phones, satellite communications, and radio astronomy, along with a scale for wavelength and frequency. Schematic diagram showing the propagation of high-frequency (shortwave) radio waves by reflection off the ionosphereSpecific ionization conditions vary greatly between day (left) and night (right), causing radio waves to reflect off different layers of the ionosphere or transmit through them, depending upon their frequency and their angle of transmission. Under certain conditions of location, ionization, frequency, and angle, multiple “skips,” or reflections between ionosphere and Earth, are possible. At night, with no intervening layers of the ionosphere present, reflection off the F layer can yield extremely long transmission ranges. refraction of HF radar radiation by the ionosphere
Britannica AI Icon

HF

frequency band
Also known as: high frequency
Written by
The Information Architects of Encyclopaedia Britannica

The Information Architects maintain a master list of the topics included in the corpus of  Encyclopædia Britannica, and create and manage the relationships between them.
The Information Architects of Encyclopaedia Britannica
Last updated

Quick Summary

Diagram illustrating the commercially used bands of the radio-frequency spectrum, with labeled sections for VLF, LF, MF, HF, VHF, UHF, SHF, and EHF. Each band shows example uses such as maritime radio, AM/FM radio, television, mobile phones, satellite communications, and radio astronomy, along with a scale for wavelength and frequency.
radio-frequency spectrum Commercially exploited bands of the radio-frequency spectrum.

HF stands for High Frequency, a radio band with wavelengths from 100 to 10 meters, corresponding to frequencies between 3 and 30 megahertz. This band is primarily used for mobile and fixed voice communication services that require transmission bandwidths under 12 kilohertz. International shortwave radio broadcasting also operates within the HF band.1

The main way HF radio transmissions travel is by reflecting off the ionosphere, a layer of the atmosphere between approximately 50 to 300 km (30 to 200 miles) above Earth. The ionosphere's reflective properties change with the time of day and solar activity. HF radio can achieve long transmission ranges, even thousands of kilometers, through multiple reflections between the Earth and the ionosphere. However, due to limitations in antenna size and power efficiency, HF is not suitable for applications like handheld personal radios or satellite transponders.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
4 Britannica Sources
  1. telecommunications media - HF
  2. HF
  3. telecommunications media - SHF-EHF
  4. telecommunications media - VHF-UHF

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.