What is the primary function of a tap port leg in a directional coupler?

The primary function of a tap port leg in a directional coupler is to supply signals to multiple dwelling units (MDUs). This tap port leg allows for the efficient distribution of a portion of the input signal to different output paths, making it ideal for applications where a signal needs to be shared among multiple receivers, such as in residential buildings or apartment complexes.

In practical terms, a directional coupler is designed to couple a defined amount of power from the input line to multiple output ports while maintaining isolation between them. This capability of tapping into the main signal path and providing output to numerous separate units ensures that all connected devices receive the desired signals without the need for a separate distribution amplifier for each unit. The design of this coupling is crucial to maintaining the integrity and quality of the transmitted signals, especially in environments where many users might be sharing the same source.

Thus, the correct answer identifies the tap port leg as an essential component for providing access to multiple dwelling units, facilitating the distribution of signals while leveraging the functionality of the directional coupler.