A novel broadband circularly polarized (CP) slot antenna array fed by asymmetric coplanar waveguide (CPW) with an inverted L-shaped strip for L-band applications is proposed. Broadband CP is obtained by an array composed of elliptically polarized elements using sequential rotation feed technique. Experimental results show that the VSWR les 1.5 impedance bandwidth and the 3-dB axial ratio bandwidth can be greatly raised to be as high as 52% (1.151.95 GHz) and 49% (1.151.9 GHz), respectively. The proposed antenna can provide a peak antenna gain of about 8 dBi at 1.5 GHz, with gain variations less than 1.5 dB for frequencies within the CP bandwidth. Good agreement is observed between simulation and measurement.