In this paper, we present a novel compact broad-beamwidth dual-band circularly-polarized(CP) antenna, named petal-shaped antenna. The antenna is composed of a petal-shaped patch and four loaded monopoles around it. The lateral size is miniaturized by adding a crossed-slot on the patch. The antenna's overall dimension is optimized to be 0.37 λ 0 × 0.37 λ 0 × 0.04 λ 0 . Its half power beamwidth(HPBW) is 170° in both the x-z and y-z planes at GPS L1 band. Thanks to its broad beamwidth and wide 3-dB axial-ratio bandwidth, it can be utilized for multiple GNSS, including COMPASS, Galileo, GPS and GLONASS.