...以写为： B d d P 4 , P 4 G max D ＝ ， ＝ 2-3-3 式中B 定义为波束面积(beam area)： max , , P d d P B 2-3-4 图2.3.1 实际抛物面反射器天线辐射方向图 72 如果在整个波束...
They reflect a concentrated beam of light onto the town's central square, creating an area of sunlight roughly 600 square meters.
它们将一束集中的光线反射到城镇的中心广场上，形成面积大约为600平方米的阳光区域。
2
In other words, ultrasound essentially travels in a very narrow beam — this makes it great for focusing the waves toward a desired area, but not for actual aural comprehension.
换言之，基本上超声波的传播声束极窄，这非常有利于将声波集中至指定地点，但对实际听力则无所助益。
3
That means the beam produced is of higher quality than other lasers, is extremely straight (even by the exacting standards of a normal laser beam) and can thus be focused onto a small area.