STUDY ON ARTIFICIAL MAGNETO-DIELECTRIC STRUCTURE FOR ANTENNA APPLICATIONS

Abstract

This thesis proposed the miniaturization of an ultra high frequency (UHF) radio frequency identification (RFID) reader antenna using an artificial magneto-dielectric material as well as a method for improving the isolation characteristic of multi-input multi-output (MIMO) antennas using split ring resonators (SRR). The first, a miniaturization of an UHF RFID reader antenna using artificial magneto-dielectric was proposed. The miniaturization was achieved using an artificial magneto-dielectric, realized using a split ring resonator (SRR). The 10 dB return loss bandwidth of the designed antenna ranges from 908.5 MHz to 914 MHz. The measured peak gain is -3.75 dBi, and the axial ratio is below 3 dB over the frequency band of interest. The second, a method to improve the isolation characteristic of MIMO antennas using SRR was proposed. The isolation characteristic of the proposed MIMO antenna was improved by using the SRR array structure between the two radiating elements. The designed antenna satisfied the 10 dB return loss bandwidth, and the isolation between the two radiating elements was less than -20 dB over the mobile-WiMAX band from 3.4 GHz to 3.6 GHz. The measured peak gains of the two elements were 2.3 dBi and 2.4 dBi, respectively. The measured envelope correlation coefficient was less than 0.2, and the mean effective gain was less than 1.5 dB.