Abstract: A new concept about the matching of signal to a network is proposed. For an n-port microwave network, if all incident waves are proportional to the conjugates of oorresponding scattermg parameters of network S* ki(i = 1 n), then the ratio of the power of scattering wave at the k-th port to the sum of power of all incident waves reaehes the maximum. Using this concept, we find some problems may be simplified when microwave networks are studied. To illustrale application of the concept, a description of an ultrabroad-band line transformer and an antenna array is given in this paper.