A Very Wideband Circularly Polarized Crossed Straight Dipole Antenna with Cavity Reflector and Single Parasitic Element
A very wideband circularly polarized (CP) crossed dipole antenna is presented in this paper. The primary radiating element of the antenna consists of two straight dipoles arranged orthogonally through double printed rings. To further enhance the axial ratio bandwidth, a cavity with proper size and single parasitic element are employed to generate two additional bands. The use of cavity reflector is investigated thoroughly, providing a solid framework for designing this type of antennas. The final design with an overall size of 0.92λo × 0.92λo × 0.32λo at the center CP frequency yields a measured –10 dB-impedance bandwidth of 75.2% and 3 dB-axial ratio bandwidth of 67.7%. The proposed antenna exhibits right-handed circular polarization and an average broadside gain of about 8.3 dBi over the CP operating bandwidth.