What Is the Antenna
What is the Antenna ?
The antenna is the device responsible of converting the electric signal confined
‘’guided’’ in the cables to a radiating waves.
Isotropic Antenna
•An isotropic antenna is a completely non‐directional antenna that radiates
equally in all directions. Since all practical antennas exhibit some degree of
directive, the isotropic antenna exists only as a mathematical concept .
•All the antenna specs will be measured relative to the isotropic antenna
(Reference antenna)
Antenna specs
1-Gain
•Defined as the ratio between the power of the max direction of the antenna to the power
obtained by an isotropic antenna in the same direction.
•Virtual gain (antenna is a passive element).
•Define for both vertical and horizontal plans.
2-BeamWidth
•Defined as the angel between the max direction to the direction where the power is
reduced to the half in the max direction.
•Represent the directive of the antenna.
•Define for both vertical and horizontal plans.
3-Tilt
•Defined as the angle between the direction of the maximum
radiation to the direction of the horizontal axes
•Define for the horizontal plane only.
•Can be achieved electrically (remotely) or mechanically.
4-Diveristy
•Defined as the redundancy in receiving and/or transmitting the
signal.
•The purpose is to overcome fading/attenuation that may be
experienced in the signal path.
•Typical gain value is (36)db.
•Three types of diversity
•Freq
•Space
The antenna is the device responsible of converting the electric signal confined
‘’guided’’ in the cables to a radiating waves.
Isotropic Antenna
•An isotropic antenna is a completely non‐directional antenna that radiates
equally in all directions. Since all practical antennas exhibit some degree of
directive, the isotropic antenna exists only as a mathematical concept .
•All the antenna specs will be measured relative to the isotropic antenna
(Reference antenna)
Antenna specs
1-Gain
•Defined as the ratio between the power of the max direction of the antenna to the power
obtained by an isotropic antenna in the same direction.
•Virtual gain (antenna is a passive element).
•Define for both vertical and horizontal plans.
2-BeamWidth
•Defined as the angel between the max direction to the direction where the power is
reduced to the half in the max direction.
•Represent the directive of the antenna.
•Define for both vertical and horizontal plans.
3-Tilt
•Defined as the angle between the direction of the maximum
radiation to the direction of the horizontal axes
•Define for the horizontal plane only.
•Can be achieved electrically (remotely) or mechanically.
•Defined as the redundancy in receiving and/or transmitting the
signal.
•The purpose is to overcome fading/attenuation that may be
experienced in the signal path.
•Typical gain value is (36)db.
•Three types of diversity
•Freq
•Space
- Freq not used in UMTS
- Space Used in UMTS
- Polarization Used in UMTS .
5-Side loops
•First side loops suppression ratio
•Front to back loop ratio.
•Side loops is important for GSM to achieve near field coverage; while
the effect for the back loop is bad as it’s adding an interference.
•The mechanical tilt affecting both the main loop only; while the
electrical tilt affecting the front and back loops.
How could we reform the antenna pattern?
•Input Current amplitude.
•Input current phase.
•Geographical shape of the radiating element.
•UMTS antenna pattern (N-array dipole)
Half-Wave Dipole (Omni) Antenna
A half-wave dipole antenna may also be used as a gain reference for practical antennas.
The half-wave dipole is a straight conductor cut to one-half of the electrical wavelength
with the radio frequency
Practical Direction Antenna
Special Thanks For my Teacher and Leader Engineer \ Abdel Rahman Fady who give me this Documents and explain it to me, without any restrictions to share it with all Students .