Wideband Circularly Polarized Antenna With Novel Asymmetric Y-Shaped Arms

A wideband circularly polarized antenna with novel asymmetric Y-shaped parasitic arms is proposed. The antenna consists of Y-shaped feedlines with vacant-quarter rings, asymmetric Y-shaped parasitic arms, rectangular patches, and a reflector. The circularly polarized radiation is generated by exciting the Y-shaped feedlines with vacant-quarter rings. The impedance matching bandwidth (IBW) and axial ratio bandwidth (ARBW) are effectively improved by introducing asymmetric Y-shaped parasitic arms, and four CP modes are introduced in the operating band. The overall dimension
s
of the proposed antenna are 0.84λ
₀
×0.84λ
₀
×0.27λ
₀
(λ
₀
is the wavelength of the center frequency in the free space), with a simple structure. The measured results show that the wide IBW covers 1.2–3.0 GHz (86%), and the ARBW is 1.3–3.2 GHz (84%). Moreover, 79% of the overlap bandwidth (1.32–3.0 GHz) is achieved between IBW and ARBW, and the measured cross-polarization discrimination is more than 18 dBic on the
Z
-axis. The antenna can be used in wireless communication due to the characteristics of wide impedance bandwidth and axial ratio bandwidth.