An Ultrawideband Circularly Polarized Antenna With Traveling-Wave Loop

A novel ultra-wideband circularly polarized (CP) crossed dipole antenna (CDA) is introduced in this letter. The proposed structure consists of two pairs of octagonal crossed dipoles, four parasitic patches, a parasitic traveling wave circular loop and 12 vertical grounded metal sheets. The design incorporates parasitic closed circular loops and vertical grounded metal sheets to enhance the impedance bandwidth (IBW) and axial ratio bandwidth (ARBW), particularly at lower frequencies. Additionally, theoretical analysis of the radiation characteristics of the traveling wave loop is also provided for comprehension. The measured results of prototype are in good agreement with the simulated results. The measured impedance bandwidth (|S11|<-10 dB) is from 1.13 to 3.83 GHz (108.9%) and the axial ratio bandwidth (AR<3 dB) is from 1.18 to 3.82 GHz (105.6%). Furthermore, the antenna exhibits a wideband 3-dB antenna gain bandwidth from 1.1 to 3.95 GHz (112.9%).