After spending a few minutes reading this article about radio communication and the science behind it, you'll have a better understanding of how radio transmission works and how this powerful technology keeps the world more informed and connected. Understanding the science behind the technology will enhance your radio shopping experience and make you a more knowledgeable two-way radio buyer and user.
The Two-Way Radio: Understanding the Transceiver
Radio communication encompasses many different technologies, from AM/FM radio stations and satellite communications to walkie-talkies, pagers and two-way radios. Though the basic science is the same, there are some key differences. A two-way radio is unique, as it acts as a both a transmitter and receiver, meaning it can both send messages and receive them. A device with this capability is also called a transceiver. For 2 people with similar radios to be able to have a conversation, they must be speaking on the same band, which is a collection of radio frequencies. This is true whether the radio is a mobile unit (installed in a vehicle), a stationary base device (at a fixed indoor location) or a hand-held portable model (a walkie-talkie).
The Electro-Magnetic Spectrum, Radio Waves and Radio Frequency
The electro-magnetic spectrum comprises all frequencies of electromagnetic radiation (EM). This EM is the radiant energy that is released by specific electromagnetic processes. Radio frequency (RF) signals form a portion of this spectrum, which also includes microwave, infrared, visible light (the visible spectrum), ultraviolet, x-ray and gamma ray.
Radio frequency (RF) signals are used by everything from Morse code and television to Wi-Fi, Bluetooth and two-way radios to transmit and receive data. These RF signals are made of electro-magnetic waves (electric and magnetic waves) which contains the audio information. The receiver antenna captures a very minute amount of transmitted power, which then has to be amplified in order to operate the earphone. Radio waves, like other types of electro-magnetic waves, are characterized by their wavelength or the frequency of their oscillations.
Radio waves are transmitted as a series of cycles. The rate of variation (oscillation) of the radio waves determines the frequency. If it passes through one cycle in a second, the frequency is said to be 1 hertz (Hz). For a radio wave passing through a cycle 100,000 times a second, the frequency is 100,000 Hz or 100KHz. Traveling at the speed of light, the distance traversed during that cycle is measured as that RF signal's wavelength. Longer wavelengths have lower frequencies. Shorter wavelengths have higher frequencies. Since RF travels by the speed of light, you can determine the wavelength by dividing the speed of light by the frequency. When transmitting and receiving radio communications, the size and shape of the components affect the signal based on its wavelength.
Wavelengths and frequencies can be thought of in more practical terms. For two-way radios, the two most popular frequency ranges are VHF (Very High Frequency) and UHF (Ultra High Frequency). VHF frequencies are best for outdoor use, as they follow the curvature of the earth, staying close to the ground. This means they can travel further in open areas. UHF frequencies, because of their shorter wavelength, can easily move through doorways, reaching a greater distance without signal degradation. UHF radios in general can better penetrate obstructions such as concrete, metal and wood, so their signal carries further indoors and around buildings or dense forests.
For more scientific information about radio communication, transmitters, receivers and antennas that can be used to strengthen a radio signal, see the radio science and technology article on Wikipedia.