因为在太赫兹（THz）波段下对物体缩比模型雷达散射截面（RCS）的测量可以减少RCS的测量周期与成本，所以太赫兹RCS计算与测量得到了更加广泛的关注。实际测量应用中，多采用类似高斯光束的太赫兹源，然而在计算中通常假定入射光为平面波。为研究这种假设给平板RCS计算结果带来的误差，计算了高斯光束入射条件下二维导体平板的RCS。仿真研究了入射光为2.52 THz激光对导体平板雷达散射截面的影响，同时与平面波入射结果进行了比较分析。计算结果显示，当导体平板宽度为20 mm时，选择波束宽度为40 mm的高斯光束作为入射光可以将误差的震荡控制在0.3 dB左右。

The measurement of radar cross section (RCS) of scale models at terahertz can decrease the cost and time of the experiments, so it attracts wide attentions. In real measurement, generally a Gaussian beam or a similar beam source is adopted，while in the RCS estimation, usually a plane wave is assumed as the incident beam. In order to study the error caused by the assumption, the RCS of a perfect conducting flat plate is estimated in two dimension when the incident beam is a Gaussian beam. In the estimation, the influence of 2.52 THz collimated laser on RCS is studied. The estimation results show that choosing beam width of 40 mm can help to keep the amplitude of the error around 0.3 dB when the width of the flat plate is 20 mm.