Antenna Types Flashcards
Omnidirectional Antenna / Rubber Duck Antenna ?
Omnidirectional antennas radiate RF signal in all directions Small, rubber-
coated dipole antenna, often referred to as a rubber duck antenna. The default antenna of many access points.
Semi-directional Antenna ?
Semi-directional antennas are designed to direct a signal in a specific direction.
Where is semi direction antenna Used ?
Used for short to medium distance communications
Types of Semi directional Antenna ?
Patch
Planer
Yagi
Patch Antenna ?
Used for outdoor point-to-point communications up to about a mile. More commonly used as a central device to provide unidirectional coverage from the access point to the clients in an indoor environment.
Planar Antenna ?
Planar antennas are also often used to provide coverage for long hallways with offices on each side
Yagi Antenna ?
They are typically used for short to medium distance point-to-point communications of up to about 2 miles, although high-gain Yagi antennas can be used for longer distances
Highly Directional Antenna ?
Highly directional antennas are strictly used for point-to-point communications, typically to provide network bridging between two buildings. They provide the most focused, narrow beamwidth
Types of Highly Directional Antenna ?
Parabolic Dish Antenna
Grid Antenna
Parabolic Dish Antenna ?
The parabolic dish antenna is similar in appearance to the small digital satellite TV antennas that can be seen on the roofs of many houses
Grid Antenna ?
The spacing of the wires on a grid antenna is determined by the wavelength of the frequencies that the antenna is designed for.
Antenna Array ?
A group of two or more antennas that are integrated together to provide coverage.
Beamforming ?
Beamforming is a method of concentrating RF energy. Concentrating a signal means that the power of the signal will be greater and the SNR at the receiver should therefore also be greater, providing a better transmission
Types of Beamforming?
Static
Dynamic
Transit
Static Beamforming?
Performed by using directional antennas to provide a fixed radiation pattern. Static beamforming uses multiple directional antennas, all clustered together but aimed away from a center point or location.
Dynamic Beamforming
Dynamic beamforming focuses the RF energy in a specific direction and in a particular shape. Like static beamforming, the direction and shape of the signal is focused. The radiation pattern of the signal can change on a frame-by-frame basis.
Transit Beamforming?
Transmit beamforming (TxBF) is performed by transmitting multiple phase-shifted signals with the hope and intention that they will arrive in-phase at the location where the transmitter believes that the receiver is located.
Antenna Polarization?
As waves radiate from an antenna, the amplitude of the waves can oscillate either vertically or horizontally It is important to have the polarization of the transmitting and
receiving antennas oriented the same in order to receive the strongest possible signal.
Polarization is not as important for indoor communications because the polarization of the RF signal often changes when it is reflected, which is a common occurrence indoors
Antenna Diversity?
Antenna diversity exists when an access point has two or more antennas with a receiver functioning together to minimize the negative effects of multipath.
Switched Antenna Diversity ?
When the access point senses an RF signal, it compares the signal that it is receiving on both antennas and uses whichever antenna has the higher signal strength to receive the frame of data. This sampling is performed on a frame-by-frame basis, choosing whichever antenna has the higher signal strength.
In which Standard Switched Antennas diversity is used ?
In 802.11n Standard
Multiple input and Multiple Output (MIMO)
Wireless radio architecture that can receive or transmit using multiple antennas concurrently. These techniques send data by using multiple simultaneous RF signals, and the receiver then reconstructs the data from those signals.
Which Standard Use MIMO?
802.11n and 802.11ac
Beamwidth ?
Measurement of how broad or narrow the focus of an antenna. Measured both horizontally and vertically from the center
or strongest point, of the antenna signal to each of the points along the horizontal and vertical axes where the signal decreases by half power.
Azimuth Chart ?
H-Plane (Top-Down View)
Elevation Chart ?
E-Plane (Side View)
