Join two antennas to eliminate the need of a rotator. Takes 75-ohm down-leads from two different antennas and combines the signals. This unit is power passive on side. With proper spacing, joining two antennas can be a great alternative to a rotator. It is recommended that you run equal lengths of coax cable from each antenna to the CC-7870 to eliminate multi-path and out of phase signals. Always join identical antennas for the best results. Using a transformer-type antenna coupler as the CC-7870 provides isolation between antennas limiting the combining loss and possible antenna loading to no greater than -3.5 dB to the output signal level.