Low-Profile Circularly Polarized Patch Antenna With Wide 3 dB Beamwidth

In this letter, a low-profile circularly polarized (CP) narrow-slots slotted-patch antenna for wide 3 dB axial-ratio beamwidth (ARBW) performance is presented. It consists of two pairs of narrow slots along the diagonal lines of a square patch with a single feed. These pairs of narrow slots are conceived and placed to serve as magnetic dipoles with quarter-wavelength separation, forcing the amplitude of the orthogonal electric field components to be equal across a wide angle. The 3 dB ARBW of the CP antenna is a strong function of the mutual magnetic field, which is feasible to alter with different parameters of the slot. The location, dimensions, and gap between the slots are tuned to achieve wide 3 dB ARBW. Measured results of the fabricated prototype exhibit 3dB ARBW of 226° with ARmin of 0.52 dB and 198° with AR
_min
of 1.61 dB in two principal planes at φ = 0° and φ = 90°, respectively. The antenna offers impedance bandwidth of 85 MHz (2.448-2.533 GHz) and CP bandwidth (CPBW) of 23 MHz (2.474-2.497 GHz). The minimum peak gain is 3.87 dBic in the broadside direction.