BSA Radio Merit Badge - Requirement Three

c. Locate on your chart at least eight radio services, such as AM and FM commercial broadcast, citizens band (CB), television, amateur radio (at least four amateur radio bands), and public service (police and fire).

Different frequencies in the Electromagnetic spectrum are used for different purposes and travel a bit differently.

Medium Frequencies – The frequencies from 300 KHz to 3 MHz are called the Medium Frequencies. The usually follow the earth’s surface using “Ground Waves” and can reach hundreds of miles. AM broadcasters are found here.

MB – MF

High Frequencies – The frequencies from 3 MHz to 30 MHz are called the High Frequencies or “HF” The usually bounce off the Ionospere using “Sky Waves” and can reach thousands of miles. Shortwave broadcasters and many Ham bands are found here

MB – HF

Very High Frequencies – The frequencies from 30 MHz to 300 MHz are called the Very High Frequencies or “VHF” The usually go right through the Ionospere and so are mostly used for line of sight communications on earth. They also can be used to talk to spacecraft. FM Radio and TV broadcasters as well as many Police, Fire and Aircraft radios operate here. The popular 6 meter and 2 meter Ham bands are found here.

MB – VHF

Ultra High Frequencies – The frequencies from 300 MHz to 3000 MHz are called the Ultra High Frequencies or “UHF” The usually go right through the Ionospere and so are used for line of sight communications on earth. They also can be used to talk to spacecraft. UHF TV broadcasters as well as some Police, Fire radios and cell phones operate here. The 440 MHz Ham band is found here.

MB – UHF