In the last module we discussed the principles of antenna and the linear dipole antennas.
The half-wavelength dipole antenna is the most commonly used antenna as it has good terminal characteristics. However, the antenna has a very broad radiation pattern and consequently low directivity.
There are many applications where we need highly directive antennas and in general a much better control of the radiation pattern. Also while doing this we wish to keep the antenna terminal characteristics more or less unaffected.
Antenna Arrays precisely is the mechanism by which we can realize complex radiation patterns without significantly altering the antenna impedance.
Here we first discuss the principle of linear arrays. The principle can be extended to the planar and volume arrays in a rather straight forward manner.
The problem of antenna arrays can be divided into two categories:
(1)Array Analysis: Here we investigate the radiation patterns for a given antenna array configuration.
(2) Array Synthesis: Here we design the array configurations to achieve a desired radiation pattern.
The array analysis problem is rather an academic exercise whereas the array synthesis is an engineering design problem. For a good design of antenna arrays, the basics understanding of array analysis is essential.
