:RG-59

{{short description|Type of coaxial cable}}

{{Refimprove|date=August 2016}}

[[File:RG-59.jpg|thumb|A section of RG-59 cable with its end stripped.

{{Ordered list|list-style-type=upper-latin

|Outer plastic sheath

|Copper braid shield

|Inner dielectric insulator

|Copper-plated core (sometimes solid core)

}}]]

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, and a capacitance of around 20pF/ft (60pF/m).{{cite web|url=http://objects.eanixter.com/PD361313.PDF |title=Product Specifications : 8261303/10 & 5571 WHRL RG59 40 1000 |website=Objects.eanixter.com |accessdate=2016-08-03}} The 75 ohm impedance matches a dipole antenna in free space. RG (for radio guide) was originally a unit indicator for bulk radio frequency (RF) cable in the U.S. military's Joint Electronics Type Designation System. The suffix /U means for general utility use. The number 59 was assigned sequentially. The RG unit indicator is no longer part of the JETDS system (MIL-STD-196E) and cable sold today under the RG-59 label does not necessarily meet military specifications.

RG-59 is often used at baseband 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 are used instead. In cases where the transmission distance is too long for these media, such options as UTP (unshielded twisted pair) or fiber optic can be used.

RG-59 coaxial cable is commonly packed with consumer equipment, such as VCRs or digital cable/satellite receivers. Manufacturers tend to include only RG-59 cables because it costs less than RG-6 does. However, given the short lengths provided (usually {{convert|4|-|6|ft|m|abbr=on|disp=or}}), this is generally sufficient for its typical use.

RG-59 is frequently used to synchronize two digital audio devices, such as ADAT optical devices. This is called word clock.