A common radio antenna is simply a conductor. It catches radio waves and essentially changes those waves into information people can see and hear. Radio antenna are usually made up of aluminum strips all laced together. It can manipulate electrical charges created by the electrical and magnetic field generated by a transmitter source--traditionally a radio broadcast station. The waves that are sent out from that broadcast station run along what is called an "electromagnetic spectrum."
When a radio station uses electrical current to send out radio waves to radio receivers, those waves travel along the electromagnetic spectrum. You can think of this spectrum as a kind of radiation rainbow. Just like there are numerous colors in a rainbow, there are different types of wavelengths and radiations. The wavelengths and radiations all have their own individual characteristics, too. They have certain sizes, shapes and sometimes even colors. A person has only to tune into those lengths and shapes to be able to manipulate and encode information on them. Typically, radio receivers are made to allow people to listen or see certain wavelengths, while tuning others out. If people did not tune certain information "out," they would not be able to decipher radio songs or even TV signals. The electromagnetic spectrum is essentially a collection of different noises, as well.
To receive a carrier wave signal, a person has to have a radio antenna. The receiver antenna essentially soaks up a sent wave, which is generally made up of excited particles. Because the particles are excited they vibrate back and forth, which creates an energy field that travels outward. Some receiver radio antennas are not the same length as a transmitter radio antenna. A CB radio antenna, however, should be the same length as the transmitter antenna. This is because the wavelength sent between antennas is a certain length and can only be manipulated using the same length. Simply, some radio antennas each have to be the same length as the actual wavelength in the air. If they are not the same length, interference may result. Interference would be interpreted as noise or annoying static.
Radio Antennas and Warfare
When people are at war with each other, they sometimes want to block the enemy's ability to receive information. Enemies often do this by blocking a radio signal that is supposed to travel to a given radio antenna somewhere--this is called interference. This simply means that an enemy can disrupt a carrier wave. A signal is sent out, for example, and the electromagnetic wave travels outward at a certain frequency (Think of frequency as how many times a wave repeats itself. It creates high and low points that are called crests and troughs). Two people can recognize two frequencies at once and essentially talk with the other--they can also opt to prevent communication. An enemy has only to change the manner in which excited particles in the air are able to travel--decelerating electrons in the air is another way people can generate radio interference.
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