Hybrid Couplers are used in RF combining, sampling and power splitting applications. A hybrid coupler is one way of combining two or more closely spaced channels together. The use of unbalanced hybrid couplers allows you to balance the insertion loss for each repeater channel, providing a more efficient system. They are also commonly used in a DAS system to properly balance each leg of the distribution system within a couple of dB. They can also be configured to sample output power levels and used as a signal sampler.