Single-Feed Wideband Circularly Polarized Antenna With Novel Parasitic Elements

A novel wideband crossed dipole loaded with four parasitic elements is investigated in this letter. The printed crossed dipole is incorporated with a pair of vacant quarter rings to feed the antenna. The antenna is backed by a metallic plate to provide an unidirectional radiation pattern with a wide axial-ratio (AR) bandwidth. To verify the proposed design, a prototype is fabricated and measured. The final design with an overall size of 0.46 lambda(0) x 0.46 lambda(0) x 0.23 lambda(0) (lambda(0) is the free-space wavelength of circularly polarized center frequency) yields a 10-dB impedance bandwidth of approximately 62.7% and a 3-dB AR bandwidth of approximately 47.2% In addition, the proposed antenna has a stable broadside gain of 7.9 +/- 0.5 dBi within passband.