大多数天线被制成碟形，用以收集和反射无线电波至亚反射器，就像曲面镜将可见光聚焦于一点一样。
Most antennas are made in the shape of a dish to collect and reflect the radio waves to the sub reflector, in the same way as a curved mirror focuses visible light to one point.
用光线矩阵方法推导了光纤-自聚焦棒-反射器在共轴耦合情况下的后向耦合系数；
The expression of retroooupling coefficient of fiber-GRIN rod-reflector in coaxial coupling is derived by ray-matrix method.
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