SOME NOVEL FREQUENCY RECONFIGURABLE ANTENNA DESIGNS

Abstract

An antenna is an integral component of a wireless communication system. Its fixed functionality or non-diversity limits the system performance. By making an antenna reconfigurable, more flexibility can be provided to the communication systems. These reconfigurable antennas allow the dynamic reconfiguration of parameters such as operating frequency, radiation pattern, and polarization. In this dissertation, some novel frequency reconfigurable antenna designs are proposed. First, a dual band discrete frequency reconfigurable ground U-slot antenna has been studied through simulations as well as experimentally. Next, a fractal Hubert curve ground slot reconfigurable antenna has been designed using PIN diode switches. The operating frequency of this antenna cover GSM and WLAN bands 1.8 GHz, 2.4 GHz, and 5.2 GHz. Finally, a self-contained frequency reconfigurable antenna system has been proposed and designed with capability of continuous tunability over a frequency band of more than oneand- a-half octave. Specifically, the antenna consists of a U-slot in the ground plane of a inicrostrip feed line. The frequency reconfigurability is achieved by mechanical variation of the slot length by means of a microcontroller controlled stepper motor which has been integrated with the antenna. The resonant frequency of the antenna has been empirically related to the slot length and a trained neural network controls the stepper motor movement for specified frequencies. The entire antenna assembly, including the stepper motor and control circuitry are housed in a RF transparent PVC hollow cylinder. These antennas have been implemented and characterized. The numerical simulations have been conducted in the Finite Integral Time Domain Method based electromagnetic simulation software package, CST Studio Suite 2012, are shown to match well with experimental results.