How Antenna can be made ?

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In our daily life we come across Antennas used for be various devices.
What is the nature of Antenna?
If a parallel wire transmission line is left open, the electric and magnetic field escape from the line and radiate into the free space. This radiation however is insufficient and unsuitable for reliable for transmission and reception.

How Antenna can be made ?

 The radiation from the transmission line can be greatly improved by bending the transmission line conductors, so that they are at right angle to transmission line. The magnetic field no longer cancel and in fact aid one another. The electric field spreads out from conductor to conductor.
 This will result into an antenna and optimum radiation occurs if the segment of transmission wire converted into antenna is one quarter wavelength long at the operating frequency. This makes an antenna that is one half wavelength longer.

In an electromagnetic wave, the ratio of electric field strength to magnetic field strength is a constant. It is called impedance of free space and also called as wave impedance and is equal to 377 ohm.

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