The performance of a spherical slot array antenna radiating circularly polarized conical beam is described in this paper. The structure of the antenna is simple and suitable for mass production. This antenna is proposed for applying to the land mobile subscriber unit located far from equator and wireless LAN system. The system of integral equation is solved by Method of Moments with the aids of dyadic Green's function. The impedance characteristics reveal the matching conditions are illustrated. The radiation characteristics such as radiation pattern and directivity are found to be conical beam radiation. The polarization characteristics are inbestigated to perform the circularly polarized radiation. The experimental results verified the theoretical ones.