Common Coaxial Cable Terms

 Air Spaced PEA coaxial cable that uses air injected into plastic– as the dielectric spacer between conductors. This is also known as a foam dielectric.


 Attenuation (Insertion Loss): Loss of power. Attenuation is usually measured in dB loss per length of cable (ex. 31.0 dB/100Ft.). Attenuation increases as frequency increases.


 Bend Radius: The radius of curvature that determines how tightly a coax cable can bend without damaging its electrical performance.


 Braid: A group of small wire strands interwoven to form a cylinder surrounding the dielectric.


 Braid Coverage: The amount that the braided filaments shield the inner dielectric. Tighter mesh materials offer a higher percentage of coverage.

Cable Attenuation– Loss or reduction in signal strength, expressed in decibels (DBS). Attenuation is a naturally occurring effect when transmitting signals over a distance.


 Capacitance: The ability of a conductor to store an electrical charge. This is measured based on the ratio between a conductor’s electrostatic charge and the difference between conductors required to maintain the charge.


 Center Conductor: The solid or stranded wire in the middle of the coaxial cable. The conductor diameter is measured by the American Wire Gauge (AWG).


 Coaxial Adapter: A device used to change one connector type to another or one gender to another (ex. BNC to SMA Adapter).


 Coaxial Cable: A two-conductor cylindrical transmission line typically comprised of a center conductor, an insulating dielectric material and an outer conductor (shielding). Coaxial cable can be flexible (typical of L-com assemblies), semi-rigid or rigid.


 Coaxial Connector: The interconnection device found at each end of a coaxial cable assembly. There are many common types of coaxial connectors such as BNC, SMA, SMB, F, etc.


 Dielectric: The insulating material that separates the center conductor and the shielding.


 Electromagnetic Interference (EMI): Electrical circuit disturbance caused by external electromagnetic induction. Also known as radio-frequency interference (RFI).


 Frequency: The number of times a periodic action occurs in one second. Measured in Hertz.


 Impedance: In simple terms, impedance, in a coaxial product, is the measurement of resistance to the flow of current. The unit of measurement is Ohms.


 The following is a more technically correct definition: Transmission line impedance, also known as characteristic impedance, is the ratio of the amplitudes of a single pair of voltage and current waves propagating along an infinitely long transmission line with the absence of any reflections. Characteristic impedance measures like resistance when dealing with coaxial cable types. Characteristic impedance is a relationship between the capacitance per unit length and the inductance per unit length. The inner and outer coaxial diameter ratios and the dielectric constant in the cable define the parameters involved in determining characteristic impedance.


 Insertion Loss: A measurement of attenuation determined by the system output before and after the connection of a cable and/or device.


 Jacket: An insulating layer of plastic or rubber covering a cable or bundle of wires.


 Microwave Frequencies: Microwave frequencies range from Ultra-High Frequency (UHF) .3-3GHz, Super High Frequency (SHF) 3-30GHz to Extremely High Frequency (EHF) 30-300GHz.


 MIL-C-17MIL-C-17 is a specification document that has been used since the 1940s to standardize the physical and electrical characteristics of coaxial cables. There is no longer any control of RG specifications so cables may perform differently than the cables that adhere to MIL-C-17.


 Plug: The male connector usually containing a center pin.

RF (Radio Frequency): A frequency band from 3 MHz to 3 GHz. Primarily used for transmission of radio and television signals.


 PTFE: Abbreviation for Polytetrafluoroethylene, also known as Teflon®. PTFE is fluoropolymer insulation or jacketing material.


 RF (Radio Frequency): The band of frequencies suitable for telecommunications, satellite, and radar.


 RG/U: Symbols used to represent coaxial cable that is built to U.S. government specifications (R=Radio Frequency, G=Government, U=Universal Specification)


 Shielding: Conductive envelope made of wires or metal foil that covers the dielectric and the center conductor


 Twinaxial: An offshoot from coaxial cabling. Two center conductors with one dielectric and braided shielding. Often used for short-range, high-speed signaling, twin axial is also known as a Twinax.


 The velocity of Propagation (VP): Usually expressed as a percentage, VP is the transmission speed of electrical energy in a determined length of cable compared to the speed of light.


 VSWR (Voltage Standing Wave Ratio): The ratio of the maximum effective voltage to the minimum effective voltage measured along an RF transmission line. This value generally increases with frequency and higher values are not desirable.