R
- Radio Frequency (RF):
The frequency range is technically broad, from about 25 kHz to 100 GHz, but the term is normally used to define the low range band of frequencies used for broadcast radio signals (including broadcast television) and extends from about 500 kHz to a few hundred megahertz.
- Rear Mounted:
A connector is rear mounted when it is insta1led from the inside of a box onto a panel. It can only be removed from the inside of the equipment. See Back Mounted.
- Receptacle:
Usually the fixed or stationary half of a two-piece multiple contact connector. Also the connector half usually mounted on a panel and containing socket contacts.
- Reflection Loss (Fiber Optic):
Energy reflected back toward a cable source. The reflections occur because the signal strikes a non-uniformity in the shield or conductor.
- Resistance:
A measure of the difficulty in moving electrical current through a medium when voltage is applied. It is expressed in ohms.
- Return Loss:
A measure of the percentage of the incident power that is reflected back down the transmission line. Return loss is the percentage reflected power expressed in dB notation.
- RG/U:
Abbreviation for Radio Guide, Universal. RG is the military designation for coaxial cable.
- RMS or rms:
Abbreviation for root-mean-square. When the term is applied to alternating voltage and current, it means the effective value; i.e., it produces the same heating effect as a direct current or voltage of the same magnitude. It is also a means of expressing a-c voltage in terms of d-c, usually approximately 70% of the a-c peak voltage.
- Rubber:
An elastic (natural or synthetic) material (e.g. silicone) used to provide waterproofing or moisture resistance. See O-ring.