This paper designes a 2×2 miniaturized broadband double-circularly polarized microstrip array antenna that works on C-band. The antenna extends the bandwidth through a multi-layer structure and the tuning stub matching technique. In order to achieve miniaturization，the T-type power divider are sequentially phase-differentiated to form a feed network，and the feed network is arranged hierarchically. The test result indicates. The impedance bandwidth of the antenna is 39.5%，and the axial ratio bandwidth both of left and right ciculary poarized is less than 3dB above 28.6%. In the 3.4GHz-4.2GHz，the gain is above 10dB.The antenna array is only 1.27λ0×1.27λ0×0.1λ0. The measured results are in good agreement with the simulated results.
