Two-Pair Slots Inserted CP Patch Antenna for Wide Axial Ratio Beamwidth

In this article, a low profile circularly polarized (CP) antenna with wide 3-dB axial ratio beamwidth (ARBW) is presented. Two-pair of parallel slots are etched on a circular patch and manifested as magnetic dipoles (MDs). These narrow slots are arranged symmetrically about the axes, and one pair is orthogonal to another pair of slots. The philosophy of CP radiation across a wide angular range strongly depends on the spacing between the paired-dipoles, for example spacing of <inline-formula> <tex-math notation="LaTeX">$0.22\lambda _{0}$ </tex-math></inline-formula>, two-orthogonal far-field radiated components become equal across a wide-angle. Moreover, this particular spacing between the paired-dipoles provides a symmetrical electric field distribution along the periphery of the patch, which ensures the broadside LHCP radiation with wide 3-dB ARBW of 228° and 214° at the plane of <inline-formula> <tex-math notation="LaTeX">$\varphi = 0^{\circ }$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\varphi = 90^{\circ }$ </tex-math></inline-formula>, respectively. The measured results from the fabricated prototype exhibit good agreement with the simulated results. The antenna has impedance bandwidth (IBW) and CP bandwidth (CPBW) of 2.6% (64 MHz), and 0.9% (22 MHz), respectively. The broadside radiation holds antenna gain higher than 5 dBic across the entire CPBW.