A broadband dual-band dual-polarized (DBDP) shared-aperture array operating at X- and S- bands for the synthetic aperture radar (SAR) application is presented.Tri-resonance is introduced in the lower frequency element to broaden its intrinsic narrower bandwidth.Furthermore

several methods are employed to enhance the polarization isolation in both bands.VSWR≤2 bandwidths of 13.1% and 11% are measured in X- and S- band

respectively

where in-band array isolation and element isolation are better than 37dB and 28dB.The measured radiation patterns match well with the theoretical ones while the cross-polarization level is suppressed under -27dB within mainlobe;the X-band scan ability of ±27° is also confirmed by the measurement.