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General Characteristics of Radio

The first theories associated with what would ultimately become radio became apparent in the early 1800s when Gian Domenico Romagnosi of Italy suggested an initial electrical synergy between current flow and magnetism. In 1820, Danish physicist Hans Christian Oersted demonstrated that a charged wire would deflect a magnetized compass needle, and he followed this awareness with the development of the first theoretical relationship between electricity and magnetism. Oersted's work helped French scientist André-Marie Ampère create the first serious effort on electromagnetism, leading to a practical awareness of radio waves and subsequently the introduction of the telegraph and the radio as consumer communications products.

  1. Directed Waves

    • Radio frequencies can be tuned to produce communications at specific points on a radio unit, such as those found on the AM/FM dial on a car unit. This is based on the characteristics of radio frequency resonance, in which the sending unit and the receiving unit agree on a particular frequency in order to create synchronous communications. Therefore, radio sometimes is referred to as a directed wave.

    Unlimited Range

    • Radio waves are the result of electromagnetic radiation based on frequencies, or the speed and length of a wave as it moves outward from its radiation point. Different radio frequency waves create different radio receiving ranges. Long waves tend to operate more efficiently at local ranges where shorter waves can reflect off the ionosphere and ultimately travel around the world. Therefore, depending on the particularly frequency, and climatic conditions radio waves can be generated on the basis of an unlimited range capability.

    Interference

    • Radio interference is essentially a process where one frequency wave is canceled by another. Typically this has to do with the signal gain, or volume, of an adjacent frequency. However, there are other limiting factors, such as physical structures that block a particular radiated frequency from reaching its intended receiver. There also are hybrid electromagnetic limitations, such as CB radio calls, that might be on the same frequency and produce enough power to overcome a local receiver.

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