为了满足**探测环境下复杂、多样化的探测需求，机载探测平台往往集成多个探测系统。共孔径复合作为一种理想的集成方式，在综合各类探测系统优势的基础上，缩减了系统的总体积，减轻了平台负担。本文计算并设计了一种卡塞格林式红外与合成孔径雷达共孔径天线。首先，根据合成孔径雷达指标设计主镜；接着，通过像差系数与非球面参数组成的方程组求解卡塞格林结构；然后，在前端卡塞格林结构、冷阑参数和红外光学系统指标的限制下，利用PW形式的像差公式计算透镜的具体结构。最终得到的雷达天线口径为1.22 m，增益为40.9 dB，红外光学系统焦距为?1 000 mm，全视场角为0.704°，次镜遮拦比小于0.33，在33 lp/mm处各温度区间MTF值大于0.4。所设计共孔径天线的各项指标均满足使用要求。

In order to adapt to increasingly complex detection environments and detection requirements, airborne detection platforms often integrate multiple detection systems. As an ideal integration method, the common aperture composite not only combines the advantages of various types of detection systems, but also reduces the total volume of the system and reduces the burden on the platform. In this paper, a Cassegrain-type common-aperture antenna of infrared and Synthetic Aperture Radars (SAR) is calculated and designed. Firstly, the primary mirror is calculated according to the radar design requirements; then, the Cassegrain structure is designed by equations consisting of aberration coefficients and aspheric parameters; next, under the limitation of the front Cassegrain structure, the cold stop parameters and infrared system parameters, the lens parameters of the infrared system are calculated by the aberration formula in PW form. The proposed radar antenna has a diameter of 1.22 m and a gain of 40.9 dB. The infrared system has a focal length of ?1 000 mm and a full field of view of 0.704°. The obscuration ratio of the secondary mirror is less than 0.33, and the MTF value is greater than 0.4 for each temperature level at 33 lp/mm. All the parameters of the proposed co-aperture antenna meet the requirements of expected applications.