20-04-2013, 04:46 PM
ANTENNA AND WAVE PROPAGATION
ANTENNA AND WAVE.pdf (Size: 976.83 KB / Downloads: 36)
Introduction
•Antenna is a Essential element in wireless system.
•Used to transmit and receiveElectromagnetic waves from free space.
•Transmission media cost is zero.
EM waves:
•Velocity :3x10^8 m/s.
•Direction of Electric and magnetic field is perpendicular to each other.
•Also Direction of Electric and magnetic field is perpendicular to direction of propagation.
•Action is similar as water waves but it is invisible.
•Standing waves.
Antennas
Receiving Antenna:Any structure designed to efficiently receive electromagnetic radiation is called a transmitting antenna
We also know that an electromagnetic field will induce currentin a wire. The shape and size of the structure determines how efficiently the field is converted into current, or put another way, determines how well the radiation is captured. The shape and size also determines from which direction the radiation is preferentially captured.
Antenna parameters
•Antenna Impedance : Technically, antenna Impedance is the ratio at any given point in the antenna of voltageto currentat that point.
•Effective Antenna aperture is the ratioof the available power at the terminal of the antenna to the power flux density .
•The gainis also called as directive gain when the antenna radiate power in a particular direction relative to the average power radiated by the Antenna.
•Directivityof an antenna is the ratio of the radiation intensity in a particulardirection and the radiation intensity averaged over all directions.
•Power Beam width (HPBW) is the anglebetween two vectors, originatingat the pattern’s origin and passing through these points of the major lobewhere the radiation intensity is half its maximum.
ANTENNA AND WAVE.pdf (Size: 976.83 KB / Downloads: 36)
Introduction
•Antenna is a Essential element in wireless system.
•Used to transmit and receiveElectromagnetic waves from free space.
•Transmission media cost is zero.
EM waves:
•Velocity :3x10^8 m/s.
•Direction of Electric and magnetic field is perpendicular to each other.
•Also Direction of Electric and magnetic field is perpendicular to direction of propagation.
•Action is similar as water waves but it is invisible.
•Standing waves.
Antennas
Receiving Antenna:Any structure designed to efficiently receive electromagnetic radiation is called a transmitting antenna
We also know that an electromagnetic field will induce currentin a wire. The shape and size of the structure determines how efficiently the field is converted into current, or put another way, determines how well the radiation is captured. The shape and size also determines from which direction the radiation is preferentially captured.
Antenna parameters
•Antenna Impedance : Technically, antenna Impedance is the ratio at any given point in the antenna of voltageto currentat that point.
•Effective Antenna aperture is the ratioof the available power at the terminal of the antenna to the power flux density .
•The gainis also called as directive gain when the antenna radiate power in a particular direction relative to the average power radiated by the Antenna.
•Directivityof an antenna is the ratio of the radiation intensity in a particulardirection and the radiation intensity averaged over all directions.
•Power Beam width (HPBW) is the anglebetween two vectors, originatingat the pattern’s origin and passing through these points of the major lobewhere the radiation intensity is half its maximum.