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 Basics of Radio Waves and Radio Transmission

 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.

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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: 

- Amplitude modulation (AM) Click for more---you will leave this web site. Please come back.

- Frequency modulation (FM) Click for more---you will leave this web site. Please come back.

- Single sideband (SSB) Click for more---you will leave this web site. Please come back.

- 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!

AM FM CW wave form SSB wave form

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!

AM vs SSB 

What is SSB?

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! 

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