Broadband Circularly Polarized Antenna With L-shaped Strip Feeding and Shorting-Pin Loading

A patch antenna with simple feeding structure for broadband circular polarization is proposed in this letter. The patch is first designed with horizontal L-shaped strip (HLS) feeding, which feeds the radiation patch at orthogonal orientations with 90^° phase difference. Two minimum points can be seen in the axial-ratio (AR) curve. By loading a shorting pin to the patch, the minimum point of lower frequency moves to higher frequency, and wide AR band is obtained consequently. Measured results show that 10-dB return-loss bandwidth of 23.6% (2.09-2.65 GHz), 3-dB AR bandwidth of 17.9% (2.18-2.61 GHz), and average gain of 8.5 dBic across the operating band are achieved for the proposed antenna with a low profile of 0.09λ₀ ( λ₀ is the wavelength in free space corresponding to 2.4 GHz).