RG-59/U is a specific type of coaxial cable, often used for low-power video and RF signal connections. The cable has a characteristic impedance of 75 ohms.

RG59 coax is often used at base band video frequencies, such as composite video. It may also be used for broadcast frequencies, but its high-frequency losses are too high to allow its use over long distances; in these applications, RG-6 or RG-11 is used instead. In cases where the transmission distance is too long for these media, such options as UTP (unshielded twisted pair) or fiber optic cable can be used. However, UTP such as Cat6 has too many twists in the twisted pairs which result as a poor choice of media for analog signals over long distances. The preferred medium is fiber optic cable.