Information about the many aspects of radio transmission
and radio waves for the ham radio operator.
by N4UJW
Hopefully this page will give you an explaination of how ham radio waves "work", the ham radio bands relationship to the radio wave spectrum, and the frequency bands in simple terms, with videos and explanations and to give you a better understanding of what is happening with your ham station when you transmit that signal in the form of radio waves. It is not all inclusive but intended to get you own your way to do your own research and study to become a better operator and the understanding of radio.
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Ham radio uses part of the lower frequency end of the electromagnetic spectrum. The chart below only shows a very small part of that spectrum.
Radio Wave Spectrum Table
The green areas in the charts below cover popular ham radio usage.
Band Name
Acronym
Frequency
Wavelength
Extremely Low Frequency
ELF
3-30 Hz
100,000 km - 10,000 km
Super Low Frequency
SLF
30–300 Hz
10,000 km – 1000 km
Ultra Low Frequency
ULF
300–3000 Hz
1000 km – 100 km
Very Low Frequency
VLF
3–30 kHz
100 km – 10 km
Low Frequency
LF
30–300 kHz
10 km – 1 km
Medium Frequency
MF
300–3000 kHz
1 km – 100 m
High Frequency
HF
3–30 MHz
100 m – 10 m
Very High Frequency
VHF
30–300 MHz
10 m – 1 m
Ultra High Frequency
UHF
300–3000 MHz
1 m – 100 mm
Super High Frequency
SHF
3–30 GHz
100 mm – 10 mm
Extremely High Frequency
EHF
30–300 GHz
10 mm – 1 mm
The chart below extends the electromagnetic spectrum even further
with examples of how each band is used.
Band name
Abbreviation
Frequency and
wavelength in air
Example uses
Tremendously low frequency
TLF
< 3 Hz> 100,000 km
Natural and artificial electromagnetic noise
Extremely low frequency
ELF
3–30 Hz 100,000 km –
10,000 km
Communication with submarines
Super low frequency
SLF
30–300 Hz
10,000 km – 1000 km
Communication with submarines
Ultra low frequency
ULF
300–3000 Hz
1000 km – 100 km
Submarine communication,
Communication within mines
Very low frequency
VLF
3–30 kHz
100 km – 10 km
Navigation, time signals, submarine communication, wireless heart rate monitors, geophysics
Low frequency
LF
30–300 kHz
10 km – 1 km
Navigation, time signals, AM longwave broadcasting (Europe and parts of Asia), RFID, amateur radio experimental
Medium frequency
MF
300–3000 kHz
1 km – 100 m
AM (medium-wave) broadcasts, amateur radio, avalanche beacons
High frequency
HF
3–30 MHz
100 m – 10 m
Shortwave broadcasts, citizens' band radio, amateur radio and over-the-horizon aviation communications, RFID, Over-the-horizon radar, Automatic link establishment (ALE) / Near Vertical Incidence Skywave (NVIS) radio communications, Marine and mobile radio telephony
Very high frequency
VHF
30–300 MHz
10 m – 1 m
FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications. Land Mobile and Maritime Mobile communications, amateur radio, weather radio
Ultra high frequency
UHF
300–3000 MHz
1 m – 100 mm
Television broadcasts, Microwave oven, Microwave devices/communications, radio astronomy, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS and two-way radios such as Land Mobile, FRS and GMRS radios, amateur radio
Super high frequency
SHF
3–30 GHz
100 mm – 10 mm
Radio astronomy, microwave devices/communications, wireless LAN, most modern radars, communications satellites, satellite television broadcasting, DBS, amateur radio
Extremely high frequency
EHF
30–300 GHz
10 mm – 1 mm
Radio astronomy, high-frequency microwave radio relay, microwave remote sensing, amateur radio, directed-energy weapon, millimeter wave scanner
Terahertz or Tremendously high frequency
THz or THF
300–3,000 GHz
1 mm – 100 µm
Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, condensed-matter physics, terahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing, amateur radio
Since it was first used around the end of the nineteenth century, radio has become a most important part of everyday life. By using radio waves, we use one of the most obvious forms of "information" transmission. Radio waves are all around us.
We use "radio" waves all the time even if we are not using ham radio.
Ring...there goes your cell phone! That's just one of the ways radio and the electromagnetic spectrum is used.
You look at your digital watch to see what time it is...that digital watch has internal circuit components that operate on some of the same principles of radio and so does that computer you are using now to view this article. Many of the same electronic principles that are used to produce computer and internet operation are a direct result of what engineers have learned about the way radio and its components work and interact with other component designs to get the desired result.
Is it time to heat up a snack in that microwave oven? There is yet another form of radio waves usage in modern day life.
If it was not for the many ways radio waves can be modified, your TV would not be working to deliver that special blockbuster movie you want to watch or hear what's happening around the world or listen to your local area news or that ball game on your favorite AM or FM radio. And those signals might be coming from a broadcast satellite several thousand miles above you in space or from one of many local broadcast radio stations on the commercial radio bands!
All of these uses of radio waves come from the modification of a carrier wave in one form or another.
As far as ham radio operators are concerned, these "forms" are called modes.
Hams use many different "modes" of radio wave modification to convey "information" of many different types from one location to another around town or to the world.
The most popular "modes" of using radio waves are listed below in no particular order:
- CW (Morse code) A simple definition: A continuous radio wave or continuous waveform (CW) in which a carrier wave is switched on and off. Information is carried by the varying duration of the on/off periods of the signal, for example by using Morse code in early radio.
- Digital Modes used in Ham radio - Some of the more frequently used modes can be found here!
CW Signal, AM and FM Waves
SSB Waves (Not animated)
Radio Waves - Videos to Help You Understand them better!
Some more helpful videos! (13 to 22 minutes long)
What is RF? Courtesy of NXP Semiconductors
More about Radio Waves and RF. (The online Engineer)
Antennas and Radio Waves - Antenna Basics from KE0OG on YouTube
Get the latest ARRL General Class License Manual from Amazon.com
More great info (You may leave Hamuniverse.com on some of the articles below) Please come back!
Frequency Modulation Basic Principles part 1 of 2 (YouTube) 1964 US Army Training Film (see same page on right side for part 2). Although made in 1964, these videos are still very accurate in their explanations of FM. Good viewing!
