Currently, passive detection of airborne targets mainly centers on radiometer imaging with real apertures and pointwise sampling imaging based on micro-element grid division. The drawback of this imaging approach is the contradiction between temperature sensitivity and scanning rate. The faster the scanning rate is, the shorter the dwell time of the antenna beam at each position, and accordingly, the system temperature sensitivity will decline. Furthermore, the enlargement of the antenna aperture is constrained by many aspects. To further enhance the resolution of passive detection of airborne targets, this paper conducts a simulation study on the detection effect of synthetic aperture radiometers for airborne targets.