Abstract-In this letter, a compact four-element microstrip patch antenna array for BeiDou navigation satellite system (BDS) operation at the B3 (1268 MHz) band is proposed. High permittivity dielectric substrate and slit-loaded microstrip patch are used to reduce the antenna element size down to 40 mm × 40 mm which implies an aperture size of only λ 0 /6 × λ 0 /6 at the B3 band. The right-handed circularly polarized (RHCP) radiation is achieved by connecting two coaxial probes to a 0 • -90 • stripline hybrid. Four identical antenna elements are distributed with the same polarity and an inter-element separation of 80 mm (λ 0 /3 at the B3 band). The overall size of the antenna array, including the stripline feeding network and supporting ground plane, is only 140 mm × 140 mm × 5.5 mm. A prototype was fabricated and measured to verify the design concept. Simulated and measured results will be presented and discussed, showing that the proposed BDS antenna array is suitable for BDS applications.