Power splitters and couplers are passive microwave components used for distributing or combining microwave signals. A splitter can be used as either a power combiner or a power divider, it is a reciprocal device. A coupler can be used to inject a second signal into a network, or as a means to sample a signal within a network (it is also reciprocal).
Couplers and splitters are usually three or four-port networks. N-way splitters are usually constructed as \"corporate\" splitters, where one two-way splitter feeds a pair of two-ways, which feed four two-ways, etc.