DESIGN AND TESTING OF A FREQUENCY RECONFIGURABLE ANTENNA

Abstract

Reconfigurable antennas are gaining much attention now a days due to the large number of researches and developments in modern communication system. Implementation of efficient reconfigurable antenna is necessary for backing up the developments in communication systems. Cognitive radio and Software defined radio are important research topics in communication systems and, the invention of efficient reconfigurable antennas are necessary for the implementation of those techniques. Sierpinski gasket monopole antenna with classical coaxial feeding gives poor impedance performance in lower resonant frequencies. So microstrip feeding was introduced in Sierpinski gasket antenna. Due to microstrip feeding the low resistance of the monopole is increased and therefore it gives a better matching characteristic. By changing the length of microstrip feed we can match the impedance at all resonant frequencies. In the present work, we have used a reconfigurable feeding for the antenna to work as a single frequency, dual frequency or tri frequency antenna. A computer controlled motor system is used to control the feed position. A laboratory prototype of the reconfigurable antenna structure was fabricated and tested for validity of the simulation results. Although the developed mechanism was tested for a fractal based multi frequency antenna, the same principle can be extended for other category of antenna structures.