Electrical Terminations Information
Electrical terminations are installed at the end of a bus or transmission line to prevent signals from reflecting back. Sometimes called electrical terminators, these electrical devices are used to prevent electrical interference.
Types of Electrical Terminations
There are four basic types of electrical terminations: chip, coaxial, SCSI, and waveguide.
- Chip terminations have a form factor of an integrated circuit (IC) chip. They are manufactured using thin-film technology.
- Coaxial terminations terminate coaxial ports.
- SCSI terminations are electrical circuits placed at each end of a small computer system interface (SCSI) cable for impedance matching.
- Waveguide terminations are devices that terminate waveguide ports.
Other unlisted or proprietary electrical terminations are also available.
Specifications
Electrical terminations differ in terms of performance specifications and category or application. Power rating, voltage standing wave ratio (VSWR), return loss are the most important performance specifications to consider. VSWR, a unit-less ratio ranging from 1 to infinity, expresses the amount of reflected energy at the input of the device. A value of 1 indicates that all the energy passes through. Any other value indicates that a portion of the energy is reflected. In terms of category or application, there are four choices for electrical terminations:
- General-purpose termination
- RF termination
- Telecommunications or telecom terminations
-
Audio / video cable termination
RF Connector Types
- BMA
- BMMA
- BNC
- Type C
- Type F
- FME
- Type G
- MCX
- MHV
-
MMCX
Connector Types
- QMA
- QWS
- SC
- SMA
- SMB
- SMC
- SSMA
- SSMA
- SSMB
- TNC
- Triax
- Twinax
- UHF
- Mini-UHF
-
ZMA
Numbered Connector Types
1.6 / 5.6
- 7-16
- 1.0 / 2.3
- 1.85 mm
- 2.4 mm
- 2.92 mm
- 3.5 mm
- 7 mm
Standards
Standards and certifications are important to consider when selecting electrical terminations. Products that are destined for sale in Europe should comply with the following European Union (UE) directives: Restriction of Hazardous Substances (RoHS), End-of-Life Vehicles (ELV), and Waste Electrical and Electronics Equipment (WEEE). Electrical terminations that are sold in the United States should comply with requirements from the Federal Communications Commission (FCC), or bear marks from Underwriters Laboratory (UL). In Canada, electrical terminations that meet requirements from the Canadian Standards Association (CSA) bear the CSA Mark, alone or with indicators.