Airshipborne radars can continuously detect targets on land， sea and in the air， it can also carry out remote sensing of the earth by the synthetic aperture radar imaging mode under the moving state. Due to the limited power supply capacity of airships， large-size antennas are required to realize long-distance target detection and remote sensing， and the weight capacity limitation of the platform also puts forward high requirements for lightweight antennas. An aireshipborne active-passive combined target detection system concept based on a sparse array is proposed especially for the low and medium altitude airship platform， which detects passively with the geo-synchronous earth orbit synthetic aperture radar being the external radiation source， the system performance under different working modes is analyzed， the method of installing the subarray antennas on the hull is presented，and the prototype manufacture and integrated installation on the hull of the lightweight antenna array are introduced.