Mechanisms of Reconfigurable Antenna: A Review

In today's evolutionary world of wireless technology, reconfigurable antenna plays a very important role. Wireless technologies such as mobile communication, military, cognitive radio, radar, satellite communication are needed to be dynamic in their functions to improve the performance in changing scenario. This can be achieved using a single reconfigurable antenna where various performance parameters like resonant frequency, polarization and radiation pattern are altered as per user end requirement. Hence, a single reconfigurable antenna replaces multiple conventional antennas resulting in a compact, low cost system. In this paper, electrical and mechanical switching mechanism for reconfigurable antennas has been reviewed. In electrical switching mechanism, reconfigurability is obtained using the p-i-n diode, Radio Frequency Micro Electro Mechanical switch (RF-MEM's) and varactor diode, where ON and OFF state of diode, activates or deactivates the part of antenna structure offering modified characteristics of antenna; while in mechanical mechanism actuators and motors mechanically modify the antenna structure. Apart from the reconfigurability mechanisms, the reviewed structures are analyzed with respect to their design theory and applications. Equivalent circuit of the diodes have been studied and presented in this paper, it being the key component in reconfigurable antennas.