利用物理光学方法分析天线的远区辐射场具有计算速度快和内存需求少的特点, 目前已被广泛应用于反射面天线的远区辐射场计算中。推导了利用斯特拉顿-朱兰成远场积分方程计算天线远区电场的表达式, 计算了某一偏馈反射面天线的方向性, 与文献中已有结果比较表明, 方向图结果是正确的。馈源的方向图模型设置为余弦函数的q次方, 利用增益公式近似推导了天线的增益, 将这一计算方法应用于赋形反射面天线的远场分析中, 通过对比反射面天线赋形前后波束扫描过程中不同扫描角度处的方向图, 验证了赋形设计对于提高天线增益平坦度的有效性。

Analysis for the radiation pattern of antennas with physical optics method is now widely used in the calculation for far field pattern of reflector antennas, which has fast computing speed and low memory requirements. The expression to calculate the far field of reflector antennas using the Stratton-Chu integral formula is derived based on surface current, and the directivity of an offset reflector antenna calculated in MATLAB is right using this method comparing with the results in the reference. The expression to calculate the gain of antennas is derived with cosqθ as pattern of the feed. The offset reflector antenna is shaped for good gain flatness during scanning in the pitching direction for 20°, and the far field pattern of shaped reflected antenna is analyzed. Results of gain of the reflector antenna in different scanning angles before and after shaping is calculated, which show that the gain flatness is improved by shaping and less time and lower memory space is taken using this method to analyse the far field pattern of antennas with physical optics method.