Coaxial cables are perhaps the most common, basic and easy-to-understand cables.
Coaxial cable (coax) is typically identified or classified according to its impedance or RG-type; for example, a 50-ohm coax or an RG-8 type.
The center conductor may be made of various materials and constructions. Most common constructions are solid or seven-strand conductors. Solid conductors are used in permanent, infrequently handled or low flex applications and stranded conductors used in flexible cable applications. Common materials include copper, tinned or silver plated copper, copper clad steel and copper clad aluminum. Plated copper is used to aid in solderability of connectors or to minimize corrosion effects. Because of a phenomena known as skin-effect, copper clad materials may be used in higher frequency applications.
Insulation, or dielectric materials, are used to provide separation between the conductors. It is desirable that the material has stable electrical characteristics (dielectric constant and dissipation factor) across a broad frequency range. The most common materials used are polyethylene (PE), polypropylene (PP), fluorinated ethylene propylene (FEP) and polytetrafluoroethylene (PTFE).
The outer conductor is typically made from a number of smaller aluminum or copper conductors combined together. These conductors are woven together to form a braid around the dielectric core. For higher frequency applications, a second braid or aluminum foil tapes are often added to improve attenuation and shield effectiveness.
The jacket material serves as a protective covering from the environment and may also serve to add in the overall flame retardant properties of the cable. Typical materials include polyvinyl chloride (PVC), PE, FEP and polyvinylidene fluoride (PVDF).
Belden® Coaxial cables are tested with equipment that simulates every known environmental and electrical performance condition. As a result, these cables can be counted on for positive, reliable and trouble-free operation.
Belden Coaxial cables are engineered in a wide selection of sizes and materials, with each offering the benefits needed for physical, electrical and cost-requirement applications. Cable choices include broadband, standard analog, precision video for analog and digital, bundled RGB, high-flex SVHS, video triax, conformable coax and more.
The cable's shielding is a very important aspect in the cable's design. To meet the various needs of our customers, Belden's coax line features a wide range of shielding options, such as:
Duofoil is a shield in which metallic foil is applied to both sides of a supporting polyester or polypropylene film.
Duobond is essentially the same construction as Duofoil (a laminated shielding tape consisting of aluminum foil/plastic film/aluminum foil), but with an extra layer of heat-sensitive adhesive bonding the foil shield to the dielectric core. This foil shield provides 100% coverage and ensures maximum shield protection.
Duobond II (Foil/Braid)
Combines all the features of Duobond with an outer braid applied for greater protection against interference and to increase the overall tensile strength.
Duobond III (Tri-Shield)
Duobond III utilizes the Duobond II design (foil/braid) plus an additional surrounding layer of Duofoil. This extra layer of foil improves shield reliability and provides an additional interference barrier.
Duobond IV (Quad Shield)
Duobond IV adds a second layer of braid to the Tri-shield design (foil/braid/foil/braid). This extra layer of braid shield provides improved strength and durability.
This shield features the same foil/braid/foil construction as Duobond II but with the additional of a shorting fold in the outermost foil. This fold prevents a slot opening from being created in the shield, thereby preventing signal egress or ingress. This unique feature creates the effect of a solid metal conduit, which improves the high-frequency performance of the cable.