Circularly Polarized Monopole Antenna with Modified Ground structure

Abstract

this paper proposes a new monopole antenna design comprises of partial modified ground structure (PMGS) with semi-circle ring shaped printed structure featured for circular polarization. At the bottom surface of FR-4 substrate, the partial rectangular ground plane is modified by adjoining two triangular patches at both the corner. Further to achieve the broader axial ratio performance, a small sized rectangular slot positioned just under the feed strip is imprinted from the partial ground plane. Proposed antenna is optimized for optimum performance before fabrication and measured for the validation with simulated results. From the measured results, it is confirmed that the antenna can be competently produced a fractional impedance bandwidth (< -10 dB) nearly $ \approx 26.40\% $ and simulated 3-dB axial ratio bandwidth ≈ 6.65 $\% ,$ respectively. The measured total gain profile is varied from 4.65 dB to 6.78 dB in impedance bandwidth; while the CP gain profile varies from 5.67 dBi to 6.28 dBi with 6.28 dBi peak gain. For the proposed antenna, the cross polar suppression was noticed around $18\;{\text{dB}}$ along with wide 3-dB beamwidth.