Antennas For Multiple Applications Vol.-i Book

Preface to the first edition
Recent wireless technology mostly depends on the microwaves and millimeter waves. To transmit these waves we require antennas. Antenna is an important and integral part of any wireless communication system. From the initial days, researchers worldwide have tried various techniques for enhancing bandwidth and efficiency of antenna structures.

Broadband antennas are such antennas which have operating bandwidth (Impedance bandwidth or fractional bandwidth) greater than 10% and high efficiency antennas generally possess radiation efficiency greater than 50%. Main advantage of broadband antennas with high efficiency is that, instead of single application these structures are useful for multiple applications.

Many approaches such as slot cutting, EBG loading, resonator loading, aperture coupling, fractal geometry, substrate removal, grooved ground plane etc. have been proposed for bandwidth and efficiency enhancement of patch antennas. Slot and resonators can be added in the ground plane or in the patch.

Fractal geometry is also useful for bandwidth enhancement but it makes a very complex geometry requiring precision fabrication. However, most of the designs reported so far could produce marginal performance enhancement. Hence there arises a need for structures which are simple, easy to fabricate and integrate with other devices and possess broadband nature with high efficiency.