Abstract: In military communication and detection systems, the gains and radar cross section (RCS) of the antenna directly affect the communication quality and stealth ability. This article proposes a circularly polarized radial line slot antenna with wideband RCS reduction that covers the operating frequency band of the antenna. The antenna adopts a spiral arrangement of Pancharatnam-Berry (PB) phase units with RLSA slot spairs, utilizing orbital angular momentum (OAM) vortex scattering waves with beam nulling in the edge direction to achieve antenna monostatic RCS reduction. In order to solve the problem of severe degradation of circular polarization performance after loading PB units, metal patches that jointly participate in radiation are loaded above the slot pairs to adjust the circular polarization radiation performance of the units. Finally, based on the theory of uniform aperture field, a circularly polarized antenna with a diameter of 11λ₀ was designed at the center frequency of 15 GHz. The peak gain of the antenna is 28.1 dBic, which is only 1 dB lower than the gain of the reference RLSA antenna, and the 10-dB RCS reduction bandwidth can be observed from 7.2 to 17.2 GHz, the measured results are in good agreement with the simulation results.