说明：  介绍了两种典型低通滤波电路及其频率特性, 结合它们的低通原型电路及其参数计算公式, 对微波低通滤波器的设计方法进行了详细介绍,并通过设计实例说明了这种通用设计方法在电路设计中的应用。
(The article in brief introduces the circuits and frequency characteristic of two kinds of typical low-pass filter and then,combined with the circuits and their parameter calculation formula, discusses a method of designing microwave low-pass filter in detail. Finally through an example the paper explains the design method in circuit application.)