Abstract:A dual-feed circularly polarized antenna with built-in harmonic-rejection capabilities is presented for the first time. The square patch antenna has been designed at 5.8 GHz and incorporates both circular polarization and harmonic-rejection in a single design, thus eliminating the need of a low-pass filter. A comparison among the proposed antenna, a simple square patch antenna, and a truncated square patch antenna is performed to evaluate the capabilities of the proposed design. The realized antenna exhibits a reflection coefficient of −1.92 dB at the second harmonic frequency of 11.6 GHz, and circular polarization for elevation angles in the range of −60 0 to 60 0 , well suited for a rectenna in wireless power transfer applications.