Axisymmetric Slot Perturbation According to Perpendicular Feed for Circularly Polarized Microstrip Antenna

Abstract

This paper presents a new, circularly polarized microstrip antenna based on an axially symmetric H-shaped slot perturbation method according to perpendicular-feed network for vehicle to nomadic devices communication system. By means of embedding the slot at the resonator due to the perpendicular feeding structure, the axis-symmetrical geometry of the slot can be obtained. As a result, the loaded axisymmetric slot provides two orthogonal operating TM modes with identical electrical lengths, that is, TM10 and TM01 modes. Also, the TM10 and TM01 modes yield a 90-degree phase differences of the electric field depending on the feeding directions. The proposed antenna successfully demonstrates circularly polarized operations with -10 dB impedance bandwidth of 2.9 %, 3dB axial ratio bandwidth of 0.8 %, the minimum axial ratio of 0.16 dB and the antenna gain of 0.52 dB at the resonant frequency of 2.4 GHz.