While i was browsing for some info to do my work. I google somethings for my hobby too.. hi... hi... hi... this is somethings good for a beginner like me to understand more bout this hobby. Coaxial is important for this hobby so here a little info bout it. source from the link in at the bottom. There are more info at that site.
- What is Coaxial Cabling?
Coaxial cable is a two conductor electrical cable consisting of a center conductor and an outer conductor with an insulating spacer between the two.
- How is Coaxial Cabling used?
Primarily, coaxial cables are used for the transmission of Radio Frequency energy. The system offers tight control over electrical impedance. This yields excellent performance at high frequencies and superior EMI control/shielding.
- Where is Coaxial Cabling used?
A broad range of applications exist for coaxial cabling. The two primary impedance values of 50 and 75 Ohms determine specific applications with 50 Ohms primarily used in data signal applications and 75 Ohms used in video signal applications.
Terms regarding coaxial usage.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.
BALUN: An acronym for
BALanced/
UNbalanced. A device commonly used to change one cabling media to another (ex. coaxial to twisted pair
balun).
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 Adaptor: A device used to change one connector type to another or one gender to another (ex.
BNC to
SMA Adaptor).
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 in nature.
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 or
electro-magnetic energy that disrupts electrical signals.
Frequency: The number of times a periodic action occurs in one second. Measured in Hertz.
Impedance: The opposition to the flow of alternating or varying current. Measured in Ohms. Two common impedance values are 50 Ohms used primarily for data and 75 Ohms used to transmit video signals.
Jack: The female connector usually containing a center socket.
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.
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.
VSWR (Voltage Standing Wave Ratio): The ratio of the maximum effective voltage to the minimum effective voltage measured along a RF transmission line. This value generally increases with frequency and higher values are not desirable.
Source :
http://www.l-com.com/content/Article.aspx?Type=L&ID=204
