Performance Enhancement of Circularly Polarized Microstrip Antenna Using Thin Slot and Magnetic Material

The performance enhancement of a circularly polarized microstrip antenna is investigated by using thin slot and magnetic material. Two different microstrip antennas with a single thin slot and a magnetic material, respectively, are employed to investigate their characteristic performances, in particular, axial ratio (AR) and impedance bandwidth. A rectangular thin slot with the size of 7.2 mm × 1 mm is arranged diagonally over the antenna patch, while a magnetic material with the size of 3 mm×3 mm × 1 mm is embedded inside the dielectric substrate of the antenna host. The magnetic material utilized for investigation is Yttrium Iron Garnet (YIG) in the demagnetized state. Characteristic performances of the proposed microstrip antenna are then compared with the ones of conventional microstrip antenna. The characterization results show that the microstrip antenna with thin slot and magnetic material can improve –10 dB impedance bandwidth for more than 78% and 44%, respectively, whilst 3 dB AR bandwidth enhances up to 12% and 160%, respectively. In addition, the center frequency of both antennas that are shifted to the lower frequency region shows the feasibility in frequency tuning and miniaturization of the microstrip antenna.