The PRL-RJ45-SMA adapter connects 8 SMA circuits to standard Cat 5 (or better) cabling.
The center pin of each SMA is connected to a signal pin on the shielded RJ45 connector, and the SMA shields and the RJ45 shield are all tied to chassis ground. Each top/bottom pair of SMAs is connected to a twisted pair in the Cat 5 cabling, based on the common TIA/EIA-568B or TIA/EIA-568A wiring, e.g:
The PRL-RJ45-SMA is designed primarily for converting differential signaling between SMAs and shielded twisted pair, but it can also be used for single-ended signaling by tying one of the SMAs in a pair to GND via an SMA termination.
If the drivers and receivers are DC coupled circuits, shielded Cat 5e or better cabling is recommended whenever the driver and receiver are separated by long distances and/or when they are supplied by different power circuits (e.g. any time the grounds on opposite ends of the Cat 5e cable are subject to ground potential differences).
A discussion of impedance matching through this adapter (and other, similar adapters) is presented here.