A Single-feed Broadband Circularly Polarized Crossed Sector Dipole Antenna

A single-feed, broadband, circularly polarized (CP), crossed sector dipole antenna is investigated in this letter. The antenna is composed of the crossed sector dipoles and achieves wideband characteristics in terms of impedance and 3-dB axial-ratio (AR) bandwidths. A pair of vacant-quarter printed rings are employed for feeding the crossed dipoles to generate CP radiation. In addition, to obtain a directional CP radiation pattern, the antenna is placed above a square reflector. The final design, with an overall size of 0.76 lambda(0) x 0.76.0 x 0.24 lambda(0) (lambda(0) is the free-space wavelength of CP center frequency), shows that it can yield an impedance bandwidth of approximately 61.1% (4.58-8.61 GHz) and a 3-dB AR bandwidth of approximately 58% (4.39-8.01 GHz). Also, the antenna has an average CP gain of 8.2 dBic across the operating bandwidth and the maximum gain of about 8.7 dBic.