Radar Definitions
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Double Shielded Armored Coaxial Cable
Coaxial Cable: A cylindrical transmission line comprised of a conductor centered inside a metallic tube or shield,
separated by a dielectric material, and usually covered by an insulating jacket. A cable with one conductor completely surrounded by another conductor, separated by a dielectric. The two conductors being coaxial. Some types of coax cables use multiple conductors surrounding each other. Normally only the inner conductor carries a signal. The outer conductors [Braid] are used as a shield, or grounded.
The term Coaxial is normally shortened to Coax.
The graphic above shows one example of a multi-conductor coax cable. This one having an armor shield or metal jacket. Cable armor is normally used in harsh environments, or when required by code. Two conductor braids are used which form the outer conductor, which is normally grounded. Using two separate braids provide better shielding than one braid alone. However, most applications do not require the added expense and protection offered by an armor covering and use some type of plastic or molded rubber to form the outer covering or jacket of the cable.
Coaxial Cable
MIL-C-17/52; 50 ohm Armored Flexible Coaxial RF Cable
1GHz operational frequency range, Solid bare copper wire.
Three additional versions of coax cable are shown in the side-bar. Although they are all coaxial cable, the difference is in the manner of shielding and number of shields used with the cable. In one case the shield is placed over an insulator which holds the lead. The other graphics show a coax with two shields, one with the shield side-by-side and one with the shield separated by an insulation layer. All three cables being placed in a covering or jacket.
Coax Cable Manufacturers, Coax Connector Manufacturers
A number of connectors may be used with a coaxial cable. Two different types are shown to the right, as a SMA connector and a BNC connector. The type of connector changes depending on the application of the cable assembly. In addition; both the connector type and coaxial cable type effect the overall characteristics of the cable assembly. For example, a consumer cables might be found using a BNC or RCA plug to receive video to a TV.
What is not depicted in any of the drawings is that the diameters of the cable changes depending on the actual type of cable. Not only can the over-all diameter of the cable change [as measured around the cable jacket], but the insulation layers, dielectric core, and inner conductors may have different diameters depending on the cable type. Also as shown, a coax cable may have any number of metal braids covering the inner conductor. In general the braid is used as a shield, which may or may not be grounded. However; there are instances when the braid is used to carry a signal. A signal or ground on the braid is possible as long as the braid is separated from the inner conductor by a dielectric core, an insulator or barrier tape.
Editor note; there are a number of military specifications that define coaxial cables. Not all military standards which define coaxial cable are listed here. In fact, as an engineer, I'm not sure how many different specifications there are, or what change in electrical or physical characteristic warrants a new specification number. Normally a change in slash number, within a specification, is clearly defined, but the cause for a new specification is not so clear.
