三种Gain的定义

Power Gain the ratio of power delivered to the load to the power delivered to the input of two port network
G=Pl/pin
Available Gain the ratio of power  available from two port network to the power available from source
G_A=Pavn/Pavs
Transducer power gain  the ratio of power delivered to the load to the power available from source
G_T=Pl/Pavs
这几个定义有什么应用价值呢?
我感觉就像文字游戏一样，

这三个定义选择的参考面不一样，适用于不同的情形。
G：不考虑负载与输入端口的反射；
G_A:不考虑输出端口反射与源反射；
G_T：不考虑负载与源反射。

谢谢，理解了。