An antenna or aerial is an arrangement of aerial electrical conductors designed to transmit or receiveradio waves which is a class of electromagnetic waves. In other words, antennas basically convert radio frequency electrical currents into electromagnetic waves and vice versa. Antennas are used in systems such as radio and television broadcasting, point-to-point radio communication, radar, and space exploration. Antennas usually work in air or outer space, but can also be operated under water or even through soil and rock at certain frequencies for short distances.
Physically, an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current, or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals. Some antenna devices (parabola, horn antenna) just adapt the free space to another type of antenna.
Samuel Finley Breese Morse (27 April 1791 – 2 April 1872) was an American contributor to the invention of a single-wire telegraph system based on European telegraphs, co-inventor of the Morse code, and a painter of historic scenes.
Morse was born in Charlestown, Massachusetts (now part of Boston), on April 27, 1791, and educated at Yale College (now Yale University). He studied painting in London and became a successful portrait painter and sculptor. In 1825 he helped found the National Academy of Design in New York City, and the following year he became the first president of the institution. He continued his painting and became a professor of painting and sculpture at New York University in 1832. About that time he became interested in chemical and electrical experiments and developed apparatus for an electromagnetic telegraph that he completed in 1836. The following year he filed a caveat, or legal notice, at the patent office in Washington, D.C., and tried without success to obtain European patents for his apparatus. He also invented a code, now known as the Morse code, for use with his telegraph instrument. Several contemporary scientists gave Morse significant financial and technical help with his work on the telegraph and Morse code.