Which active DAS component is responsible for coupling input signals from donor systems?

A coupling antenna is a passive element used to receive over-the-air RF signals from a donor base station and is not an active component performing signal coupling within the DAS architecture.

A bidirectional amplifier (BDA) serves as the active interface between the donor system (such as a base station or donor antenna providing the macro network signal) and the DAS distribution network. It amplifies downlink signals from the donor into the DAS for remote antenna distribution, and simultaneously couples uplink signals from the DAS back to the donor. This bidirectional, active coupling role makes it the component responsible for interfacing donor signals into the active DAS.

A transceiver is the root head-end element of the DAS that originates the signal source, not the component specifically designated for coupling incoming signals from an external donor system.

A receiver is a one-directional device that only accepts incoming signals and cannot perform the bidirectional coupling required to properly interface a donor system with the DAS distribution path.