How Does a Ham Radio Antenna Work?
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Operator License Required
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The FCC (Federal Communications Commission) grants licenses to hobbyists allowing transmission of radio waves for personal, non-commercial use. These licensed amateurs are called ham radio operators. The ham description actually applies to the operator person, not the radio. The reason for the word has been lost to history, however many think it is a shortened derivative of the word amateur. An understanding of the ham antenna begins with an understanding of the transmitter and an understanding of radio wave frequency
Role of the Antenna
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The ham radio antenna is the last step of the outgoing message signal process and the first step of the incoming message process. The antenna usage starts at the energy supplied by an alternating current source, namely electricity. The transmitter modulates, which means changes, the energy to allow a signal to be impressed upon it. The transmitter sends this altered energy, which now contains a signal, to the ham antenna. The antenna converts this alternating current containing the signal to an electromagnetic wave that moves in space. The receiving antenna operates in reverse manner; the electromagnetic wave is intercepted by the ham antenna that reduces it to electric current which is demodulated to a usable signal that the radio is tuned to accept.
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Antenna Types
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The simplest antenna design is the dipole, having a single wire feed with directed element, such as aiming the old television rabbit ears antenna. A fat dipole antenna has multiple feed wires at points on the dipole which provide wider frequency. The word fat describes the wider frequency rather than the physical size of the antenna. The J-pole antenna has two distinguishing features; it has a multi-directional pattern that begins at a low take off angle. The Yagi antenna is named for the Japanese inventor in the 1920s and is sometimes called a beam antenna. The distinguishing feature of this type is the antenna is aimed at a single direction, thereby enhancing quality of signal. This antenna type is quite popular because it allows for strong signal and conversations with another single operator.
Installation Factors
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Most antennas are constructed of aluminum, a very good conductor, and should never be serviced during rainfall. Calculation of wind load at the area of installation and the decision on the use of a wind tower and the requirement of proper grounding are factors that are essential parts of a safe and effective ham antenna installation.
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Resources
- Photo Credit http://en.wikipedia.org/wiki/Amateur_radio
