The Active Loop Port (two red banana jacks) is used to connect a Loop Cable when using Ubidium as an Active System.
Ubidium can support loop cables between 5 meters (~16 ft) and 60 meters (197 ft) in length, which should be setup with a width between 30cm (11 inches) and 60cm (22 inches).
Longer cables may result in power degradation which will inhibit the ability of the system to provide 100% Loop Power.