Antenna Theory - Antenna Arrays

An antenna, when inspanidually can radiate an amount of energy, in a particular direction, resulting in better transmission, how it would be if few more elements are added it, to produce more efficient output. It is exactly this idea, which led to the invention of Antenna arrays.

An antenna array can be better understood by observing the following images. Observe how the antenna arrays are connected.

An antenna array is a radiating system, which consists of inspanidual radiators and elements. Each of this radiator, while functioning has its own induction field. The elements are placed so closely that each one pes in the neighbouring one’s induction field. Therefore, the radiation pattern produced by them, would be the vector sum of the inspanidual ones. The following image shows another example of an antenna array.

The spacing between the elements and the length of the elements according to the wavelength are also to be kept in mind while designing these antennas.

The antennas radiate inspanidually and while in array, the radiation of all the elements sum up, to form the radiation beam, which has high gain, high directivity and better performance, with minimum losses.

Advantages

The following are the advantages of using antenna arrays −

The signal strength increases

High directivity is obtained

Minor lobes are reduced much

High Signal-to-noise ratio is achieved

High gain is obtained

Power wastage is reduced

Better performance is obtained

Disadvantages

The following are the disadvantages of array antennas −

Resistive losses are increased

Mounting and maintenance is difficult

Huge external space is required

Apppcations

The following are the apppcations of array antennas −

Used in satelpte communications

Used in wireless communications

Used in miptary radar communications

Used in the astronomical study

Types of Arrays

The basic types of arrays are −

Colpnear array

Broad side array

End fire array

Parasitic array

Yagi-Uda array

Log-peroidic array

Turnstile array

Super-turnstile array

We will discuss these arrays in the coming chapters.