## Ham radio operators often refer to frequency. This one word refers to a great deal more than you may think.

If you spend even a few minutes around a ham radio operator, you will soon hear him or her talk about "frequency." Frequency refers to how many complete electromagnetic wave cycles occur in one second. Radio signals are actually electromagnetic waves that travel very quickly.

The electromagnetic spectrum is the entire range of frequencies of electromagnetic waves. AM and FM stations occupy just a small portion of that spectrum. Other portions, or bands, are taken up by TV and shortwave stations and other communications. Still other parts of the spectrum include x-rays, microwaves, and visible and infrared light rays. Their location on the electromagnetic spectrum depends upon their frequency. In the United States, the Federal Communications Commission (FCC) allocates, or gives permission to use, certain portions of the electromagnetic spectrum to different users.

Most people are familiar with the term frequency when it is used to talk about AM or FM broadcast stations. For example, an FM station may broadcast at a frequency of 103.5 MHz. The unit "MHz" means "megahertz" or one million cycles per second. So, the radio signals from a station broadcasting at a frequency of 103.5 MHz are transmitting at 103,500,000 cycles per second. AM and FM broadcast stations are assigned a specific frequency at which they broadcast.

Unlike AM or FM radio, however, ham radio operators operate over certain ranges of frequencies rather than just one specific frequency. Rather than say the frequency ranges by number, though, hams will usually refer to the frequency ranges by their approximate wavelength.

Wavelength is a measure of how far the electromagnetic wave travels in a single cycle. The faster a signal's cycle, the less distance it can travel in one cycle. As a result, the lower the frequency, the longer the wavelength and the higher the frequency, the shorter the wavelength. For example, the 3.500-3.750 MHz frequency range has a wavelength of approximately 80 meters while the 144.1-148.0 MHz frequency range has a wavelength of approximately 2 meters.

There are several frequency bands that ham radio operators are allocated for use by ham radio operators. Ham radio operators are granted certain privileges in certain bands based upon their FCC license class. There are currently three classes of licenses being issued by the FCC: technician, general, and amateur extra. Beginning with technician class in which no Morse code is required, each advancing class of license requires additional written and Morse code tests but also grants additional frequency privileges.

In the past, the FCC issued three additional classes of licenses: novice, technician plus, and advanced. Even though no new licenses are being issued in these classes, some operators still hold these licenses and have certain privileges granted by those licenses.

In addition to frequency bands and operating class, operators also have certain emission privileges that vary from band to band. Emission refers to the type of radio signal the ham radio operator is transmitting. Here are some common emission types:

1. CW - Morse code

2. Phone - voice communication

3. Image - television and facsimile communications

4. RTTY/Data - an abbreviation for "radioteletype," this now refers to digital communications

5. MCW - Morse code using a keyed audio tone

Finally, ham radio operators are limited to certain levels of transmitter power. The power limitations vary from band to band.

This is just a brief introduction to ham radio frequency. More information can be found from the FCC or the American Radio Relay League (ARRL).

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