802.11a — The IEEE standard that specifies a carrier sense media access control and physical layer specifications for 54 megabit per second wireless LANs transmitting at 5 GHz.

802.11b — The IEEE standard that specifies a carrier sense media access control and physical layer specifications for 5.5 and 11 megabit per second wireless LANs transmitting at 2.4 GHz.

802.11g — The IEEE standard that specifies a carrier sense media access control and physical layer specifications for 54 megabit per second wireless LANs transmitting at 2.4 GHz.

AMPS — Advanced Mobile Phone Service; the analogue wireless transmission standard (technology) deployed in the 1980s in the United States and Canada. AMPS operates at 800 MHz. See also N-AMPS (Narrowband AMPS).

Antenna — A wireless system component that converts wired electrical energy to wireless radio waves, and directs them through the air in some pattern.

Antenna Array — An antenna comprising a number of radiating elements, generally similar, which are arranged and excited to obtain directional radiation patterns.

Axial Ratio — The ratio of the axes of the polarization ellipse.

Band — A clearly defined range of radio frequencies dedicated to a particular purpose.

Bandwidth — The range of frequencies within which the performance of the antenna, with respect to some characteristic, conforms to a specified standard. Greater bandwidth generally provides for a more robust system because changes in the installation environment will not degrade antenna performance.

Bi-directional — Communications between two points where each point both transmits and receives.

Beamwidth — In a plane containing the direction of the maximum of a beam, the angle between the two directions in which the radiation intensity is one half the maximum value of the beam.

Bluetooth — A short range wireless standard operating at 2.4 GHz. Originally designed for use as a cable replacement technology, it is now used for personal area networking. For a comparison of frequency bands, please visit CNN's Wireless 101 Definitions

CDMA — Code Division Multiple Access (CDMA) is one of several digital wireless transmission methods in which signals are encoded using a pseudo-random sequence that corresponds to a different communication channel, that the receiver also knows and can use to decode the received signal. CDMA is one of several "spread spectrum" techniques. CDMA offers improvements over analogue transmission in the areas of reduced call dropping, battery power conservation, more secure transmission and increased service options. For a comparison of frequency bands, please visit CNN's Wireless 101 Definitions

Coax — Short for coaxial cable.

Coaxial Antenna — An antenna comprised of an extension to the inner conductor of a coaxial line and a radiating sleeve which in effect is formed by folding back the outer conductor of the coaxial line.

dB — DeciBels; a technique for expressing voltage, power, gain, loss, or frequency in logarithmic form against a reference. Typical references include volts, watts or Hz. DeciBels are calculated using the expression: dB = 10*log(x/y)

dBi — A ratio of decibels to an isotropic antenna that is commonly used to measure antenna gain. The greater the dBi value, the higher the gain and, as such, the more acute the angle of coverage.

DCS 1800 — Digital Cellular System. Also known as GSM 1800 or PCN, this digital network operates in Europe and the Asia Pacific. It is another name for GSM working on a radio frequency of 1800 MHz.

Dipole — A type of low gain antenna consisting of two (often internal) elements.

Directional Antenna — An antenna having the property of radiating or receiving electromagnetic waves more effectively in some directions than others.

Diversity Antenna — An intelligent system of two antennas that continually senses incoming radio signals and automatically selects the antenna best positioned to receive it.

Embedded Antenna — Typically an antenna that is enclosed into a product's housing or case, or one that is not readily discernible by a casual observer. The antenna forms an integral, inseparable part of the product.

Frequency — The number of times an electromagnetic wave goes through a complete cycle in one second, measured in Hertz.

Gain — In a given direction, 4 pi times the ratio of the radiation intensity in that direction to the net power accepted by the antenna from the connected transmitter.

GHz — Gigahertz; one trillion cycles per second (a measure of frequency).

GPS — GPS is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. A GPS receiver uses these "man-made stars" as reference points to calculate positions accurate to a matter of meters.

Ground Plane — A conducting or reflecting plane functioning to image a radiating structure.

GSM — Global System for Mobile Communications; the digital transmission technique widely adopted in Europe and supported in North America for PCS. GSM uses 900 MHz and 1800 MHz in Europe. In North America, GSM uses the 1900 MHz. See also CDMA, PCS, TDMA. For a comparison of frequency bands, please visit CNN's Wireless 101 Definitions

Input Impedance — The impedance presented by an antenna at its terminals.

Isolation Between Antennas — A measure of power transfer from one antenna to another - the ratio of power input to one antenna to the power received by the other, usually expressed in decibels.

Isotropic — A hypothetical antenna having equal radiation intensity in all directions.

Line of Sight — An unobstructed straight line between two transmitting devices. Line of sight is typically required for long-range directional radio transmission. Due to the curvature of the earth, the line of sight for devices not mounted on towers is limited to 16 miles (26km).

Li-Ion — Lithium-Ion batteries offer more energy per volume than Nickel based cells, with a low self-discharge rate. Li-Ion batteries are lighter in weight than earlier battery types, have a relatively long cycle life and generally do not suffer from a memory effect, with disadvantages including more complex charging and protection circuitry, and a higher cost.

Li-Poly — Lithium-Polymer batteries are lighter in weight than even Li-Ion batteries, have a relatively long cycle life and generally do not suffer from a memory effect. Their advantages include a very thin form factor, no toxic substances, and a low self-discharge rate. Their disadvantages include their high cost and more difficult assembly.

MHz — Megahertz, a measure of frequency in millions (mega) of cycles per second.

NiCd — A Nickel Cadmium battery is durable, rechargeable and typically has an extremely long life cycle. NiCd battery advantages include low cost, high current delivery and simple charging systems. Disadvantages include a high self-discharge rage of 30% per month, caustic contents, and a large size as compared to other battery types.

NiMH — Nickel Metal Hydride battery is a rechargeable battery that is capable of holding more power that a NiCd battery and suffers much less from memory effect. It is also typically more expensive than a NiCd battery. NiMH battery's disadvantages include a high self-discharge rate of 30% per month and a heavy weight per unit volume.

Omni-Directional Antenna — An antenna having an essentially non-directional pattern in azimuth, and a directional pattern in elevation.

PCS — Personal Communications Service (or System.) Generally, a marketing term used to describe a wide variety of two-way digital wireless service offerings operating at 1900 MHz. PCS services include next generation wireless phone and communication services, wireless local loop, inexpensive walk-around communications service with lightweight, low-powered handsets, in-building cordless voice services for business, in-building wireless LAN service for business, enhanced paging service as well as wireless services integrated with wired networks. A Personal Communications System refers to the hardware and software that provide communications services.

PIFA — Planer Inverted F Antenna.

Polarization — In a given direction, the polarization of the wave radiated by the antenna. Alternatively, the polarization of a plane wave incident from the given direction which results in maximum available power at the antenna terminals.

Radome — An enclosure for protecting an antenna from the harmful effects of its physical environment, generally intended to leave the electrical performance of the antenna unaffected.

Radiation Pattern — (antenna pattern) A graphical representation of the radiation properties of the antenna as a function of space coordinates.

Reverse Polarity TNC (RP-TNC) — A connector type unique to NetWORLD radios and antennas. Part 15.203 of the FCC rules covering spread-spectrum devices limits the types of antennas that may be used with transmission equipment. In compliance with this rule, NetWORLD, like all other wireless LAN providers, equips its radios and antennas with a unique connector to prevent attachment of non-approved antennas to radios.

RF — The area (or band) of the electromagnetic spectrum where most radio communication takes place, typically from 100 KHz to 100 GHz.

SAR — Specific Absorption Rate; the amount of radiation absorbed by the human body (SAR for the entire body) or by the head (local SAR).

SMT — Surface Mount Technology, whereby electronic components are machine-mountable to the surface of printed circuit boards.

Stubby Antenna — A short thick monopole.

TDMA — Time Division Multiple Access is one of several technologies used in digital wireless transmissions that increases the efficiency of the network by allowing a greater number of simultaneous transmissions. Networks using TDMA assign 6 timeslots for each frequency channel. Devices using the wireless network send bursts of information that are reassembled at the receiving end. For a comparison of frequency bands, please visit CNN's Wireless 101 Definitions

Telematics — The convergence of wireless technology, Global Positioning Systems (GPS), onboard electronics, asset tracking and information services.

UMTS — Universal Mobile Telecommunications System; an international third-generation (3G) wireless communications system capable of supporting very-high-speed mobile multimedia services.

VSWR — A comparison of the power accepted to the power reflected back from the system, generally with respect to a 50 Ohm line impedance. A VSWR of 1.0 is 100% of power accepted by the antenna, a VSWR of 1.5 is 97%, a VSWR of 2.0 is 89%.

WAP — Wireless Application Protocol; a wireless telephony protocol that transforms a wireless handset into a mobile Internet and multimedia device.