Microstrip-Fed Broadband Circularly Polarized Antenna for Lower UWB

In this paper, a wide band circularly polarized open-ended hexagonal slot antenna is presented in this letter. The open-ended hexagonal slot is excited by the asymmetrical feed line in order to obtain circular polarization. The asymmetrical feed along with the open-end assists in exciting the slot to generate the necessary orthogonal modes for the circular polarization, which are equal in magnitude and opposite phase. Furthermore, to the hexagonal slot an open end is introduced at one of its corners. The open-end of the hexagonal slot provides additional perturbations which helps in improving the axial ratio bandwidth (ARBW). A parametric study is performed to improve the antenna performance. The presented design has a wide impedance bandwidth from 3 to 10.4 GHz and a broad ARBW of 66.6% (4–8 GHz). The proposed antenna has fabricated on a FR4 substrate (ɛr = 4.4, tanδ = 0.025) of thickness 1.58 mm and has a compact size of 40 mm × 40 mm. The measured results are in good agreement with the simulated ones.