抛物线的焦点

Feed positioning in the way that its phase center exactly coincides with the focus of the offset parabola and its direction so that the radiation maximum falls in the geometric center of the elliptic reflector surface are not intuitive at all, as in classic parabolic antennas.

馈源用这样的方式定位——其相位中心准确位于偏馈抛物线反射器的焦点，方向也要准确，这样辐射最大值才能落在椭圆形反射面的几何中心，这样一点也不直观，正如标准的抛物面天线。

The reason for this is that ratio F/D determines the angle the edges of the parabola are seen from the focus.

原因就是F/D的比率限定了抛物线焦点到边缘的角度。

Focus of the parabola, practically, is in the entrance in the waveguide of the converter.

抛物线的焦点实际上是在变频器波导入口处。

A calculation method and calculation results that show that a new kind of shaped paraboloid antennas can produce a ringy radiation pattern is presented.

通过数值计算发现将抛物线绕通过焦点的非抛物线对称轴旋转而形成的赋形抛物面天线可产生环状的方向图主瓣(此主瓣指的是主瓣最大值处)。

The specificity of the surface gained in this way is that when the beam of rays parallel to its axis of rotation falls on it, the beam is reflected so that all the rays meet in one point, known as the focus, in the same way that optical lenses focus light rays in their focus.

抛物线的表面或曰抛物面，是由抛物线围绕其对称轴旋转而成，其特点是，和抛物线对称轴平行的射线波束被抛物面所反射，所有的电波都在同一点汇聚， 1 September，2009 3D 角反射天线作馈源的 5.8GHz 偏馈抛物面天线我们把这点叫做焦点。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。