Antennas

Antennas Antenna act as transmitter and receiver for radio signal A transmitting antenna takes waves that are generated by electrical signals inside a device such as a radio and converts them to waves that travel in an open space. The waves that are generated by the electrical signals inside radios and other devices are known as guided waves and The waves that travel in an open space are usually referred to as free-space waves

Distance

Antennas properties: 1- Direction: Is the shape of transmission pattern. is the shape of the wireless signal after leaving the antenna. Directivity is an important quality of an antenna. It describes how well an antenna concentrates radio waves in a given direction .

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Antennas properties Gain - Is a measure of increasing in power. The gain of an antenna is essentially a measure of the antenna’s overall efficiency.

Antenna rating Antenna are rated in : 1- Isotropic antenna: - Theoretical antenna with uniform three dimensional radiation pattern. Radiate or receives energy equally in all direction. an isotropic antenna is often used as a reference antenna for the antenna gain 2- Dipole antenna : - Real antenna , have a different radiation pattern. - Dipole antennas can be oriented horizontally, vertically

Omni directional antennas - Called non directional (Radiate or receive in all direction)

Directional antenna