Antennas are used to transmitted and receive radio waves. An antenna is a length of copper wire or similar material, with one end free and the other end connected to a receiver or transmitter. When transmitting the radio waves created by the electronic circuit of the transmitter are fed to this antenna. This sets up an electrical pressure (voltage) along the wire, which will cause a small electrical current to flow into the antenna. Because of the current is alternating , it flows back and forth in the antenna at the same frequency as the radio waves, it creates both a magnetic field and an electrical field around the antenna. This continuous (analog) combination of magnetism and electrical pressure moves away (propagates) from the antenna . The results is an electromagnetic wave(EM wave).
J. L. Olenewa (2014). Guide to Wireless Communications, ( Third Edition). Boston:CENGAGE Learning
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