Antenna arrays assignment ,introduction,Type,Examples and Application & usage of arrays antenna Antenna arrays assignment ,introduction,Type,Examples and Application & usage of arrays antenna

1. Antenna Arrays
Introduction
An antenna array is group of antennas connected and arranged in a regular structure
to form a single antenna that is able to produce strong radiation patterns
An antenna array (or array antenna) is a set of multiple connected antennas which
work together as a single antenna, to transmit or receive radio waves
Basics of arrays antenna
Antenna array is used to modify the radiation pattern. Generally it is used to increase
the directivity of the antenna.
 Usually, arrays have many applications. But, these are most often used to
improve the gain and shape the radiation pattern of an antenna system
effectively.
Examples of Arrays Antenna
 Collinear array.
 Broad side array.
 End fire array.
 Parasitic array.
 Yagi-Uda array.
 Log-peroidic array.
 Turnstile array.
 Super-turnstile array.

2. Types of antenna

3. ARRAYS ANTENNA TYPES
There are two (2) types of array antenna
A broadside array is a one or two dimensional array in which the
direction of radiation (main lobe) of the radio waves is
perpendicular to the plane of the antennas. To radiate
perpendicularly, the antennas must be fed in phase.
An endfire array is a linear array in which the direction of radiation
is along the line of the antennas. The antennas must be fed with a
phase difference equal to the separation of adjacent antennas.
There are also arrays (such as phased arrays) which don't belong
to either of these categories, in which the direction of radiation is at
some other angle to the antenna axis.
 Parasitic Array: Used for controlling radar and various other
narrow beams such as the microwave communication system
 Driven Array: Radiating elements are connected to an energy
source and have less loss when compared to parasitic arrays, but
still maintain the narrow beam characteristics. The driven arrays
are used as search radar antennas where narrow beams are less
critical when compared to low losses

4. Explaination:
An antenna array is an assembly of radiating elements. Radiation pattern of a single
element is relatively wide, each element provides low values of directivity. However,
in many applications we require antennas with very high directive characteristics.
The directive characteristics of the antennas can be improved by increasing the
electrical size of the antenna.
For instance:
The dipole antenna allows better control of direction than an isotropic antenna, but
as length of the dipole increases, control direction may decrease. More control and
flexibility can be easily regained for beam direction with a multiple radiator
arrangement. VHF sector reflective-array
Factors of Array Antenna
Array Factor and Array Pattern of a Phased Antenna Array. Antenna arrays are
an important class of antennas which are widely used in point to point
communication systems
GAIN:
An antenna array can achieve higher gain (directivity), that is a narrower beam
of radio waves, than could be achieved by a single element
Radiation pattern
The radiation pattern of such an antenna consists of a strong beam in one
direction, the main lobe, plus a series of weaker beams at different angles
called sidelobes, usually representing residual radiation in unwanted
directions.
Directivity
Directivity is also defined for an antenna receiving electromagnetic waves its
directivity when receiving is equal to its directivity of transmitting. The
directivity of an actual antenna can vary from 1.76 dBi for a short dipole, to as
much as 50 dBi for a large

5. Application and Usage of Arrays antenna
There are multiple usage & find different applications for antenna array.
1. increase the overall gain
2. provide diversity reception
3. cancel out interference from a particular set of directions
4. "steer" the array so that it is most sensitive in a particular direction
5. determine the direction of arrival of the incoming signals
6. to maximize the Signal to Interference Plus Noise Ratio (SINR
7. Broadcasting
8. Beamforming
9. Naval usage
10. optical phased arrays
11. Radio-frequency identification (RFID)
12. Weather research usage
13. Missiles guidance
14. Fire radar aircraft
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ASAD ALI CHANG