Antenna is mostly used for Radio waves due to which it is often referred as 'Radio Antenna'. Radio waves are electromagnetic waves which carry signals through the air (or through space) at the speed of light with almost no transmission loss. The first antennas were built in 1888 by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of electromagnetic waves predicted by the theory of James Clerk Maxwell.
An antenna is an Impedance matching and directing device. It is an electrical device which converts the electrical currents into radio waves or radio waves into electrical currents. Since they are directing devices they are used with transmitters and receivers. Antennas are arrangements of electrical conductors. These conductors are electrically connected to transmitters or receivers. The antenna at the receiver intercepts the small amount of EM wave and develops tiny voltage which forms small current this current is amplified at the receiver.
When a two wire transmission line is open circuited at the ends it will have a standing wave pattern with voltage maximum at the end of the line. From quarter wave from the end it will have a minimum. The transmission line looses very little amount of energy because field of each wire cancels each other. By folding that wire we form a dipole antenna. Now both fields are added.The name dipole is given due to it has to electrical poles not the physical poles.
Maximum power will be emitted from the Antenna if it follows the maximum power transfer theorem. Which is matching the impedance of an antenna system to the complex conjugate of impedance of transmitter or receiver system. ANY piece of conducting material will work as an antenna on any frequency. The reason for building sophisticated antennas is to allow us to Control The Radiation Pattern for maximum efficiency and effectiveness.
Antennas are basically two types according to technology: Omnidirectional and Directional (in one or two direction).
Although according to their structure and application antennas are of various types...
An antenna is an Impedance matching and directing device. It is an electrical device which converts the electrical currents into radio waves or radio waves into electrical currents. Since they are directing devices they are used with transmitters and receivers. Antennas are arrangements of electrical conductors. These conductors are electrically connected to transmitters or receivers. The antenna at the receiver intercepts the small amount of EM wave and develops tiny voltage which forms small current this current is amplified at the receiver.
When a two wire transmission line is open circuited at the ends it will have a standing wave pattern with voltage maximum at the end of the line. From quarter wave from the end it will have a minimum. The transmission line looses very little amount of energy because field of each wire cancels each other. By folding that wire we form a dipole antenna. Now both fields are added.The name dipole is given due to it has to electrical poles not the physical poles.
Maximum power will be emitted from the Antenna if it follows the maximum power transfer theorem. Which is matching the impedance of an antenna system to the complex conjugate of impedance of transmitter or receiver system. ANY piece of conducting material will work as an antenna on any frequency. The reason for building sophisticated antennas is to allow us to Control The Radiation Pattern for maximum efficiency and effectiveness.
Antennas are basically two types according to technology: Omnidirectional and Directional (in one or two direction).
Although according to their structure and application antennas are of various types...
Types of antenna will be posted soon...
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