As the name implies, an RF/microwave power divider will split an input signal into two equal and identical (i.e. in-phase) signals. It can also be used as a power combiner, where the common port is the output and the two equal power ports are used as the inputs. Important specifications when used as a power divider include the insertion loss, return losses, and amplitude and phase balance between the arms. For power combining of uncorrelated signals, such as when performing accurate intermodulation distortion (IMD) tests like IP2 and IP3, the most important specification is the isolation between the input ports.