An antenna array applied to spaceborne Global Navigation Satellite System(GNSS) radio occultation has been discussed. It can cover GPS L1/L2 and BD2 B1/B2 frequency bands. The array unit is built up by double-layered air chamber circular polarized antennas. Construction of this array is formed of an H-type. Its elements amplitude and phase are optimized in the design with simulation and differential evolution algorithm, thus broadening the azimuth beamwidth，reducing the number of array and its weight，simplifying the network design without any effect on its electrical performance. As is shown in the test results, the azimuth beamwidth≥±42.2°，the elevation beamwidth of±6.4°，phase center stability up to ±1.67 mm within ±40°azimuth. Simulation and experimental results demonstrate the design is practical in engineering.