A CB radio or (citizens band) radio is the perfect medium range
communications tool. The average store bought 2 way radio usually
operates on GRMS or FRS frequencies. These frequencies are limited to a
few miles and are limited even further by buildings, tress, mountains
and all obstacles. CB radios can obtain ranges up to 150 miles,
sometimes more. CB's operate on a different frequency than traditional
consumer radios which allows them to obtain these extended ranges and
makes them a preferable communications tools.
Frequencies
Radio waves are electro-magnetic waves that rely on antenna to cast their signal. Radios can oscillate at a certain frequency to receive or transmit these waves. Megahertz means millions of cycles per second, so when a signal is measured in say 500 megahertz it means that frequency is oscillating at 500 million times per second. As an example here are the common frequencies used in the world.
o AM radio - 535 kilohertz to 1.7 megahertz
o Short wave radio - bands from 5.9 megahertz to 26.1 megahertz
o (CB) Citizens band radio - 26.96 megahertz to 27.41 megahertz
o TV stations - 54 to 88 megahertz for channels 2 through 6
o FM radio - 88 megahertz to 108 megahertz
o TV stations - 174 to 220 megahertz for channels 7 through 13
Antennas
Antennas work best with their radios when the length of the antenna matches the wavelength being transmitted. CB radio begins at 25.01 megahertz meaning that the antenna would need to be just over 39 feet to match the wavelength. A simple way to measure is using this common formula.
Wavelength (in feet) = 984 / frequency (in megahertz)
Obviously 40 feet is a bit long for most cars or even houses for that matter so people tend to use antennas that are a fraction of their proper length such as 1/2, 1/4, 1/8 or 5/8ths.
There are roughly 40 channels in the CB spectrum but obviously it's not feasible to have an individual for each frequency. To compensate most antennas lie somewhere in the middle of the spectrum to access as many channels as possible. This does waste some power as not all of the electricity is transmitted properly into radio frequencies.
Types of CB Radios
There are basically two types of CB radios; portable ones or stationary ones. The portable CB has a much smaller range due to a small antenna but operates wonderfully with a nearby Base station which has a long range. Many opt to buy a base station for use in the car since it has complete functionality and can be used with the antenna in their car or a separate antenna at home. Below are some examples of CB radios.
Base CB radio - Cobra 148 GTL
The 148 GTL is the best CB you can buy without spending a fortune. This CB utilizes sideband, a frequency in between the main frequencies, to give you not just the full 40 channels but an additional 40 sideband channels. For privacy and performance this is the right radio.
Portable CB Radio - Cobra Compact/ Remote Mount
This radio is an all in one CB with portability for every situation. This is a great example of modern technology mixing with the classic portable CB.
Shooting Skip
Some people believe that CB radios are limited to 50-300 miles, they are wrong. Although it's technically illegal (in the US) many hobbyists choose to shoot their radio signals up into the ionosphere, which during heavy sunspot activity can reach areas across the world. Since shooting skip relies on the radiation from the sun, if there is limited sun spot activity it may not be possible to shoot skip at all. Likewise long periods of sun activity make it possible to talk to places around the world for long periods of time. The only exception to this is during mid summer when there is erratic sunspot activity, although it is highly unpredictable.
Frequencies
Radio waves are electro-magnetic waves that rely on antenna to cast their signal. Radios can oscillate at a certain frequency to receive or transmit these waves. Megahertz means millions of cycles per second, so when a signal is measured in say 500 megahertz it means that frequency is oscillating at 500 million times per second. As an example here are the common frequencies used in the world.
o AM radio - 535 kilohertz to 1.7 megahertz
o Short wave radio - bands from 5.9 megahertz to 26.1 megahertz
o (CB) Citizens band radio - 26.96 megahertz to 27.41 megahertz
o TV stations - 54 to 88 megahertz for channels 2 through 6
o FM radio - 88 megahertz to 108 megahertz
o TV stations - 174 to 220 megahertz for channels 7 through 13
Antennas
Antennas work best with their radios when the length of the antenna matches the wavelength being transmitted. CB radio begins at 25.01 megahertz meaning that the antenna would need to be just over 39 feet to match the wavelength. A simple way to measure is using this common formula.
Wavelength (in feet) = 984 / frequency (in megahertz)
Obviously 40 feet is a bit long for most cars or even houses for that matter so people tend to use antennas that are a fraction of their proper length such as 1/2, 1/4, 1/8 or 5/8ths.
There are roughly 40 channels in the CB spectrum but obviously it's not feasible to have an individual for each frequency. To compensate most antennas lie somewhere in the middle of the spectrum to access as many channels as possible. This does waste some power as not all of the electricity is transmitted properly into radio frequencies.
Types of CB Radios
There are basically two types of CB radios; portable ones or stationary ones. The portable CB has a much smaller range due to a small antenna but operates wonderfully with a nearby Base station which has a long range. Many opt to buy a base station for use in the car since it has complete functionality and can be used with the antenna in their car or a separate antenna at home. Below are some examples of CB radios.
Base CB radio - Cobra 148 GTL
The 148 GTL is the best CB you can buy without spending a fortune. This CB utilizes sideband, a frequency in between the main frequencies, to give you not just the full 40 channels but an additional 40 sideband channels. For privacy and performance this is the right radio.
Portable CB Radio - Cobra Compact/ Remote Mount
This radio is an all in one CB with portability for every situation. This is a great example of modern technology mixing with the classic portable CB.
Shooting Skip
Some people believe that CB radios are limited to 50-300 miles, they are wrong. Although it's technically illegal (in the US) many hobbyists choose to shoot their radio signals up into the ionosphere, which during heavy sunspot activity can reach areas across the world. Since shooting skip relies on the radiation from the sun, if there is limited sun spot activity it may not be possible to shoot skip at all. Likewise long periods of sun activity make it possible to talk to places around the world for long periods of time. The only exception to this is during mid summer when there is erratic sunspot activity, although it is highly unpredictable.
Article Source: http://EzineArticles.com/?expert=Sirrae_Parker
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