Single-feed dual-band circularly polarized asymmetric four-arm curl antenna

This paper presents a single-feed dual-band circularly polarized composite cavity-backed four-arm curl antenna. A pair of vacant-quarter printed rings is utilized in the feeding structure to produce good impedance matching and circular polarization (CP). A cavity-backed reflector is employed to improve the CP radiation characteristics, such as 3-dB axial ratio beamwidth and broadside gain. Dual-band operation is obtained with different arm lengths in the four-arm curl structure. The proposed antenna can be very useful in dual-band applications with a small frequency ratio.