Why antennas are used in advanced low power concepts??

An antenna can be defined as any wire, or conductor, that carries a pulsing or alternating current.An electromagnetic field around the wire and that field will pulse and vary as the electric current does. If another wire is placed nearby, the electromagnetic field that cross this wire will induce an electric current that is a copy of the original current, only weaker. If the wire is relatively long, in terms of wavelength, it will radiate much of that field over long distances. The simplest antenna is the “whip”. This is a quarter wavelength wire that stands above a groundplane.

The most common examples are found on automobiles and are used for broadcast radio, CB and amateur radio, and even for cellular phones. This design goes back to the 1890's when Marconi set out to prove that radio signals could travel long distances.