GLOSSARY A

3 PLUS 3 - A National Missile Defense System using satellites and ground-based radars deployed close to the regions from which threats are likely. The space-based system would detect the exhaust plume from the burning rocket motor of an attacking missile. Forward-based radars and infrared-detecting satellites would resolve smaller objects to try to distinguish warheads from clutter and decoys. Based on that data, the ground-based interceptor -- a hit-to-kill weapon -- would fly toward an approximate intercept point, receiving course corrections along the way from the battle management system based on more up-to-date tracking data. As the interceptor neared the target its own sensors would guide it to the impact point. [10:2606] See also BALLISTIC MISSILE DEFENSE (BMD).

3D-iD - A Local Positioning System (LPS) that is capable of determining the 3-D location of items (and persons) within a 3-dimensional indoor, or otherwise boundaried, space. The system consists of inexpensive physical devices, called "tags" associated with people or assets to be tracked, and an infrastructure for tracking the location of each tag. [10:2657] NOTE: Related technology applications include EAS, EHAM, GPS, IRID, and RFID.

A-POLE - The distance between a missile-firing platform and its target at the instant the missile becomes autonomous. Contrast with F-POLE. [10:27]

ABSORPTION - (RF propagation) The irreversible conversion of the energy of an electromagnetic WAVE into another form of energy as a result of its interaction with matter. See also ELECTRO-OPTIC PAINTING and RADAR CAMOUFLAGE. [3]

ABSORPTIVE CHAFF - CONFUSION REFLECTORS which consist of extremely thin conductors, graphite strands, or other material which will absorb electromagnetic energy. See also CHAFF. [8]

ACOUSTIC BULLET - A NONLETHAL WEAPON consisting of a high-power, very low frequency acoustic beam weapon that incapacitates by creating plasma in form to the target, generating an impact wave like that of a blunt object. It causes blunt object trauma, as opposed to that of a conventional bullet which cause ripping and tearing of the target. [10:2341] See also SONIC BULLET.

ACOUSTIC JAMMING - The deliberate radiation or re-radiation of mechanical or electro-acoustic signals with the objectives of obliterating or obscuring signals which the enemy is attempting to receive and of deterring enemy weapon systems. [1]

ACOUSTIC SIGNATURE - The noise emitted by a ship to the water used by passive sensors. This NOISE is further defined as broadband or narrow-band to help define both its source by the ship and its utility to the sensor. See also BROADBAND NOISE, NARROWBAND NOISE. [10:126*]

ACOUSTIC WEAPON - A device, which may or may not be a NONLETHAL WEAPON, that emits sonic frequencies causing such sensations as debilitating dizziness and motion sickness or nausea, and can also generate vibrations of body organs resulting in extreme pain, seizures, or death. [10:2730] See also HIGH POWERED ACOUSTIC WEAPON, SILENT SOUND DEVICE, THERMAL GUN. Note: Acoustic weapons may be grouped as shown below: [10:2748]

ACOUSTIC WEAPON CHARACTERISTICS
TYPE	FREQUENCY	TARGET EFFECTS	PROPAGATION CHARACTERISTICS
Infrasound	Less than 20 Hz	Mild to severe discomfort; organ functional disturbance; organ disruption	Ground or structure penetration Long-range propagation Non-directional
Sonic	20 Hz to 20 KHz	Hearing interference; performance degradation; pain; hearing loss; tissue damage	Moderate propagation and moderate directionality
Ultrasonic	20 Khz and above	Possible diffuse psychological effects; pain; surface tissue damage; tissue destruction	Limited propagation; highly directional

ACOUSTO-OPTIC (AO) RECEIVER - A SIGINT receiver which process signals using BRAGG CELLs. In these cells, RF signals are converted into acoustic waves which are then sampled with light beams. AO receivers share the positive features of MICROSCAN RECEIVERs, and have good signal probability of intercept (POI). [10:2561]

ACOUSTO-OPTICS - The interaction between sound and light in a crystal. This interaction modifies the light beam's amplitude, frequency, phase and direction, thus processing and revealing information carried by both the sound and the light. Acousto-optics has application in ESM for analysis of low-probability-of-intercept FREQUENCY HOPPING signals. See also BRAGG CELL. [10:29] NOTE: In a typical application, a laser beam is expanded, spatially filtered, and collimated by a set of lenses which direct the beam to a Bragg cell. Concurrently, a transducer on the cell converts the micro-wave signal into an acoustic wave that modulates the light beam, producing a separate beam for each component frequency of the signal and deflecting the beam in proportion to its frequency. A photodetector array detects each beam's position (its underlying frequency), and produces electric output indicating both the frequency and power of each component in the original microwave signal. This rapid signal processing allows accurate measurement of the signal's pulse timing and duration.

ACTIVE AIR DEFENSE - Direct defensive action taken to nullify or reduce the effectiveness of hostile air action. It includes such measures as the use of aircraft, air defense weapons, weapons not used primarily in an air defense role and ELECTRONIC WARFARE. See also AIR DEFENSE. Contrast with PASSIVE AIR DEFENSE. [1]

ACTIVE ARMOR - Armor designed to dynamically thwart damage to a vehicle. It is comprised of explosive cassettes containing embedded sensors to detect an impacting projectile and to decrease it's damaging effect on the vehicle. Active armor includes ELECTROMAGNETIC ARMOR, REACTIVE ARMOR and SMART ARMOR. []

ACTIVE ARRAY RADAR - A phased array radar in which each radiating element contains a transmitter and receiver front end, as opposed to a single transmitter/receiver serving all phased array elements. Advantages attributed to active array radars include efficient use of prime power, no waveguide losses, very wide bandwidth, extreme reliability, and potential for ARTIFICIAL INTELLIGENCE (AI) features, such as simultaneously performing radar surveillance, communications and weapon control, among others. [10:2537]

ACTIVE DENIAL SYSTEM - A NONLETHAL WEAPON (NLW) that uses pulses of electromagnetic energy to heat the water molecules in a person's skin, causing a painful burning sensation but no actual burning. [10:2883] NOTE: The ACTIVE DENIAL SYSTEM is designed to disperse disruptive crowds as far as 640 meters away without injuring the demonstrators. The radiation can penetrate clothing but will only react with skin to a depth of less than 0.4 mm. These weapons can be either hand-held, vehicle mounted, or mounted on aircraft.

ACTIVE ELEMENT ARRAY (AEA) - A phased-array system having an independently controlled active transmit and receive function for each radiating element. [10:2677] See also PHASED-ARRAY ANTENNA.

ACTIVE EXPENDABLE DECOY (AED) - An RF DECOY separated some distance from the protected platform and which transmits a signal greater in amplitude than that of the SKIN PAINT of the protected craft in order to capture the threatening missile and decoy it away from its target. [10:65]

ACTIVE HOMING GUIDANCE - See also HOMING GUIDANCE. Contrast with PASSIVE HOMING GUIDANCE, SEMI-ACTIVE HOMING GUIDANCE. {JOINT PUB 1-02} A system of homing guidance wherein both the source for illuminating the target, and the receiver for detecting the energy reflected from the target as the result of illuminating the target, are carried within the missile. [1]

ACTIVE LOADING - A STEALTH TECHNIQUE in which the protected platform generates a false ECHO whose amplitude and phase can be used to cancel real radar echoes from several directions simultaneously to avoid detection by a network of radars. []

ACTIVE MAGNETIC BEARING (AMB) -- An alternative to conventional bearings, AMB consists of a journal mounted on a rotating shaft surrounded by a stator (electromagnetic coils) that exerts magnetic forces to keep the shaft suspended. [10:2652]

ACTIVE MATRIX LIQUID CRYSTAL DISPLAY (AMLCD) - A type of LIQUID CRYSTAL DISPLAY (LCD) . The elements are controlled by a matrix of thin-film transistors (TFTs). An active semiconductor element -- a transistor or diode -- is located at each pixel location. AMLCDs provide full color, active motion video and readability in sunlight. They are thin compared to CATHODE RAY TUBEs (CRTs), have very low power requirements, good environmental characteristics, no convergence or distortion problems, are light-weight, rugged, and offer color purity and brilliance. AMLCDs are gradually replacing cathode ray tubes (CRTs) in most weapons systems. [10:2518] See also REFRACTIVE LIQUIDS.

ACTIVE MAWS - A MISSILE APPROACH WARNING SYSTEM (MAWS) which generally employs PULSED DOPPLER RADAR as its sensor. This radar is able to discern a moving target in stationary or slow-moving background clutter. Further, it permits determination of range information and more precise ANGLE-OF-ARRIVAL (AOA) data. Since use of a radar precludes stealthy operation, and because missile detection distance is generally limited due to low RADAR CROSS SECTIONs (RCSs), the use of active MAWS has some disadvantages over that of PASSIVE MAWS. [10:2558]

ACTIVE PROTECTION SYSTEM (APS) - A system composed of a FREQUENCY-AGILE, MILLIMETER-WAVE radar able to detect and track incoming antitank guided missiles, and an active countermeasure suite. [10:2585] See also SLID NOTE: APS is essentially a "bullet-on-bullet" technology which involves very high velocity rounds and a very short reaction time, with virtually no room for error. [10:2905]

ACTIVEX (ActiveX) - A computer scripting language, developed by Microsoft Corp., by which small programs, called "controls" can be downloaded from the Internet and executed. [10:2619] See also JAVA. NOTE: Once a user's browser downloads an ActiveX control from a site, the control remains on the user's computer. So when the user visits another site (or another page on the site) using the same control, it need not download the control again.

ADAPTIVE BATTLESPACE AWARENESS (ABA) - The ability to provide a common operating picture to provide relevant information to commander-in-chief (CINC), joint task force (JTF), and component-level SITUATIONAL AWARENESS (SA), decision-making, execution, and planning for future military operations by providing user-customized templates and filters; providing links to relevant amplifying information such as TARGETING, intelligence products, status, etc.; introducing new force-level track types; and facilitating information aggregation at the CINC and JTF levels. [10:2881]

ADAPTIVE CONTROL - A control system that adjusts the response from conditions detected during the operation. [12]

ADAPTIVE FILTER - An electronic FILTER that automatically adjusts to changing signal conditions. [10:58] NOTE: Adaptive filters are used in receivers to reject interfering signals such as those caused by JAMMING or unintentional interference.

ADAPTIVE OPTICS SYSTEMS - Optical systems that compensate for the effects of the atmosphere and other phase distortion sources. []

ADAPTIVE SCHEDULER - An ADAPTIVE CONTROL feature of a sensor that can automatically change DWELL and REVISIT times, depending upon the threat environment, e.g., more visits to identify targets, and minimal visits to threat sectors containing hostile countermeasures such as anti-radiation missiles. [10:2812]

ADDRESS HYGIENE - The computerized process of analyzing postal address lists and modifying data in order to increase the accuracy of the data. For example, a set of duplicate addresses may exist because the street address on one record is abbreviated, e.g., "Av.", and the other spelled out, e.g., "Avenue"; one task of address hygiene might be to spell out all abbreviations (e.g., "Dr" and "Dr." changed to "Drive", "Av", "Av." and "Ave" changed to "Avenue", "Rd" and "Rd." changed to "Road", etc...). More sophisticated techniques might include Zip Code correction, telephone area code corrections, name standardization, automatic checking of public records to check for irregularities and errors, as well as other cleansing tasks to improve data quality and create a more consistent and reliable database free of duplicate records. []

ADVANCED BATTLESPACE INFORMATION SYSTEM (ABIS) - A federation of systems that forms an underlying grid of flexible, shared and assured information services and provides advanced capabilities in support of new command and control and force employment concepts. It blends rapidly emerging commercial technologies with advanced military research to deliver comprehensive knowledge to war fighters at all levels. ABIS comprises a collection of distributed data and applications integrated through a grid of supporting services. [10:2593] NOTE: Development of ABIS would entail an orderly progression from existing STOVEPIPE systems to overarching technology capabilities in less than 15 years (1997).

ADVANCED ELECTRO-OPTICAL SYSTEM (AEOS) - A 3.67 meter telescope located on the island of Maui. AEOS will have seven coude rooms for various experiments, as well as conventional Cassegrain positions located on the mount itself. Le coude is French for "elbow" - meaning the light is "bent" from the telescope through a coude path to the basement of the facility. From the basement, the light is redirected to the appropriate laboratory for data collection, analysis, or experiments. [10:2804]

ADVANCED ENCLOSED MAST/SENSORS (AEM/S) -- A large composite structure (approx. 90 feet high by 35 feet in diameter) designed to reduce the RADAR CROSS SECTION (RCS) of structure. The upper half of the hexagonal mast, intended to pass own-ship sensor frequencies, is covered with a FREQUENCY SELECTIVE SURFACE (FSS); the lower half can be reflective or covered with RADAR ABSORBING MATERIAL (RAM). The mast encloses a variety of antennas. The mast serves the dual purpose of protecting its contents from the elements and reducing the overall RCS of the vessel. [10:2658] NOTE: An AEM/S was installed on the USS Arthur W. Radford (DD-968) in May of 1999. [10:2672]

ADVANCED GUN SYSTEM (AGS) -- A 155 mm gun mount designed with low radar and infrared signatures. The gun will be capable of firing ballistic and precision-guided munitions to ranges up to 100 nautical miles. [10:2659]

ADVANCED INTELLIGENT NETWORK (AIN) - A National Communications System (NCS) network which can provide access control, priority treatment, user authentication, and other survivability features supporting National Security and Emergency Preparedness (NS/EP) telecommunications. It is a service-independent architecture introduced into the Public Switched Network (PSN) that will provide technical and cost advantages and end-user control over service definition, service customization, and choice of equipment suppliers, as well as the ability to modify and manage their services without telecommunications service provider intervention. View the 1999 AIN architecture. [10:2806]

ADVANCED JOINT EFFECTIVENESS MODEL (AJEM) -- A tri-service developed computer simulation model designed to be the DoD standard computer simulation for evaluating the lethality and terminal effectiveness of munitions and the vulnerability of aircraft, missiles, and ground-mobile systems.
[ http://ajem.survice.com/globals/ajem_home.html ]

ADVANCED LIGHTWEIGHT INFLUENCE SWEEP SYSTEM (ALISS) - A system which uses new magnetic and acoustic technology to defeat "smart" multisensor sea mines designed to discern real targets from spoofs. Its magnetic technology feature uses closed-cycle, conductively cooled, superconducting magnets arranged in a 5-ft diameter circle that emulates the dipole magnetic moment of assault craft. The acoustic technology feature uses plasma-discharge, pulse-power techniques in three "spark-gap" electrodes to discharge electrical pulses that simulate the sound of the Landing Craft, Air Cushioned (LCAC). [10:2691]

ADVANCED SWIMMER DELIVERY SYSTEM (ASDS) - A dry mini-submarine with a two-man crew, capable of clandestine and covert insertion and recovery of a Navy SEa-Air-Land (SEAL) squad or Special Operations Forces (SOF) troops. The ASDS can be launched from a submarine or from the well-deck of an amphibious ship. []

ADVANCED TETHERED VEHICLE (ATV) - A tethered, unmanned vehicle system designed for operation at great sea depths. It employs multiple television cameras to provide three-dimensional views of its work area. []

ADVANCED THREAT INFRARED COUNTERMEASURES (ATIRCM) - An aircraft survivability system which performs the functions of missile warning, INFRARED jamming and expendable dispensing. The system features a coordinated, multispectral response from its directable jammer and dispenser that is CUED by either an electro-optical or infrared missile warning subsystem. The missile warning sensors detect all types of missile threats (not just infrared), thus can provide data to other aircraft survivability equipment (ASE). [10:2547]

ADVANCED UNITARY PENETRATOR (AUP) - A sub-caliber (i.e., smaller diameter) high density penetrator employing ultra-high density tungsten explosives to achieve increased target penetration. The penetrator is carried in a larger-caliber light-weight round which provides the aerodynamic characteristics needed for accuracy. []

AERIAL DIVERSIONARY DEVICE - A NONLETHAL WEAPON consisting of a multi-shot capability to distract individuals or crowds. In crowd control, it can be used to provide a warning shot by delivering a flash-bang projectile over the heads of a violent or potentially violent crowd to allow other troop formations to maneuver to more advantageous positions. [10:2857]

AEROSOL - (1) (laser-maser) A suspension of small solid or liquid particles in a gaseous medium. Typically, the particle sizes may range from 100 micrometers to 0.01 micrometers or less. [3] (2) Solid, resonant-size particles dispersed in the atmosphere, and having a high index of refraction. The particles both scatter and absorb visual and laser energy so as to reduce the effectiveness of weapon systems directed by these techniques. [4:1] NOTE: The particle size and type are chosen to scatter or absorb radiation from electro-optical system targets. Some forms of aerosols can partially absorb microwave signals. [8]

AFFORDABLE MOVING SURFACE TARGET ENGAGEMENT (AMSTE) - The ability to employ airborne sensor resources to fix, track and engage with precision, moving surface threats from long ranges and in all weather conditions. [10:2849]

AGENT - (1) In VIRTUAL REALITY, a software program that can carry out fairly sophisticated tasks in unknown networked environments without human intervention; in other words a "smart" BOT. [10:2595] (2) A software component that performs one or more common tasks by acting in a preset manner. Agents may be classified as to characteristics (mobility - stationary or mobile); response method (deliberative or reactive); autonomy; learning; and specific task to be performed (e.g., interface). [10:2624] Also called SOFTWARE AGENT.

AIRBEAM TECHNOLOGY - A textile manufacturing technology which employs continuous braiding or weaving of a high-strength, three-dimensional fabric sleeve over an air-retention bladder, thus providing a seamless high-strength structure. [10:2739] NOTE: A few applications for airbeam technology includes rapid deployable space structures, deployable wings, pollution containment, inflatable antennas, and beamless supports for temporary field hangars and other field shelters.

AIRBORNE DATA RELAY (ADR) - A communications system used to extend data link ranges of UNMANNED AIR VEHICLES (AUV) or to bend a line-of-sight data link around obstacles, such as mountains. []

AIRBORNE ELECTRONIC ATTACK (AEA) - A MISSION area consisting of three activities: (1) the nonlethal SUPPRESSION OF ENEMY AIR DEFENSES (SEAD), i.e., electronic jamming of radars and related communications; (2) the lethal suppression, or destruction of enemy air defenses (DEAD), i.e., use of missiles or other munitions to physically destroy enemy radars and related infrastructure; and (3) self-protection, or use of JAMMING and DECOYS to render missiles harmless to the attacking aircraft. [10:2879] See also ELECTRONIC ATTACK.

AIRBORNE LASER (ABL) - A DIRECTED ENERGY WEAPON (DEW) designed to deliver a lethal LASER beam onto a ballistic missile during the highly vulnerable boost phase of flight. The system autonomously will detect and locate a missile seconds after launch using a series of INFRARED sensors that work in tandem to target the missiles. [10:2589] The ABL consists of three critical laser systems linked by mirrors. The primary mirror both gathers in light beams and focuses them outward; other mirrors reflect the laser beams, split them, sometimes into two separate beams of different wavelengths (diachronic mirrors), steer them, and, for the killing beam, shape its wavefront. A megawatt CHEMICAL OXYGEN IODINE LASER (COIL) is the primary killing beam. [10:2607] See also BALLISTIC MISSILE DEFENSE (BMD).

AIRBORNE OPTICAL ADJUNCT (AOA) - A hump-backed Boeing 767 which carries a large long-wave-length infrared sensor. Used to collect data on reentry vehicles. [10:66]

AIRBORNE REMOTE OPTICAL SPOTLIGHTING SYSTEM (AROSS) - A digital camera mounted in a stabilized turret located on the underside of an aircraft that flies over a beach area. The camera collects time series data about a beach surf in the area. Analysts then examine the behavior of breaking waves to determine the location of mines in the surf. [10:2896] NOTE: This is not yet (2001) a REAL TIME system.

AIRBORNE STANDOFF MINEFIELD DETECTION SYSTEM (ATAMIDS) - (Army) A dual-mode high-resolution INFRARED system using LASER sensors. Very high resolution radars are used to locate mines lying on the surface of the ground, while infrared sensors, able to distinguish slight temperature differences, will be used to detect shallowly buried ordnance. The sensor is designed to be carried in a short-range UNMANNED AIR VEHICLE (UAV). [10:2529]

AIRBORNE TARGETING AND CROSS-CUEING SYSTEM (ATACCS) - A system designed to task multiple sensors automatically on individual targets, thereby decreasing the target-search and data-analysis time requirements of present (1999) reconnaissance systems. [10:2692]

AIR-CHISEL MINE CLEARING - A mechanized method that employs high-pressure air to rapidly uncover soil, leaves, and other debris down to and around a suspected mine without causing mine detonation. [12.1] See also WATER-JET MINE CLEARING.

AIR COMBAT MANEUVERING INSTRUMENTATION (ACMI) - A system of aircraft-mounted pods designed to capture all the moves and countermoves in airborne training exercises for monitoring, real-time kill notification, and post-mission debriefing. [10:2644]

AIR DEFENSE - All defensive measures designed to destroy attacking enemy aircraft or missiles in the earth's envelope of atmosphere, or to nullify or reduce the effectiveness of such attack. See also ACTIVE AIR DEFENSE, PASSIVE AIR DEFENSE. [1]

AIR DEFENSE ALERTING DEVICE (ADAD) - A stand-alone guide for a soldier carrying a stinger missile. It can be fully integrated with a multiple gun or surface-to-air missile vehicle. A control panel assigns priorities for targets based on speed and direction. Several missile batteries can be tied into the unit. The system detects aircraft coming head-on from INFRARED emissions from wing edges or helicopter rotor blades. It is designed to reject false signals from sources such as birds. It is claimed that the infrared detector's passive nature renders it immune to ELECTRONIC COUNTERMEASURES. Similarly, it cannot be detected or targeted by anti-radar missiles. [10:2543]

AIR SURVEILLANCE - The systematic observation of air space by electronic, visual, or other means primarily for the purpose of identifying and determining the movements of aircraft and missiles, friendly and enemy, in the air space under observations. See also COMBAT SURVEILLANCE, SEA SURVEILLANCE, SURVEILLANCE. []

ALIASING ERRORS - Errors arising in sampled-data systems when the input signal is sampled too slowly (at under twice the frequency of the highest- frequency component of the input signal). []

ALL-GAS CHEMICAL LASER - A CHEMICAL LASER which creates its light by combining two specific gases: nitrogen chloride and atomic iodine. The device is expected to be relatively light in weight, operate in zero-gravity environments and possess a built-in heat rejection exhaust. [10:2854]

AMPLITUDE - The amplitude of a sinusoidally varying quantity (WAVE) is the maximum, or peak, value of this quantity. [3] NOTE: Sometimes the rms (root-mean-square) value of the wave is used to characterize the amplitude of a sinusoidal oscillation.

AMPLITUDE MODULATION EQUIVALENT (AME) - A method of independent sideband transmission in which the carrier is reinserted at a lower level after its normal suppression to permit reception by conventional AMPLITUDE MODULATION (AM) receivers. []

ANALYZER JAMMING - A SELF-SCREENING or SUPPORT ECM technique that analyzes the received radar signal and then transmits back to the radar a false ECM-oriented signal that has the appearance of a legitimate signal, but which is actually offset in range and/or azimuth from the actual target return. [8]

ANALOG RADAR - A radar (e.g., earlier radar system) that employs analog means, such as timing circuits, for system control and signal processing. Contrast with DIGITAL RADAR. [10:2389] NOTE: Analog radars are susceptible to drift, internal and external radio frequency interference, and to temperature and humidity variations.

ANECHOIC TILE - SONAR reflectors/sound absorbers designed to provide confusing echoes. [10:41*] NOTE: Anechoic tiles are analogous to CHAFF.

ANGELS - [In EW] (1) Radar interference from natural sources. [8] (2) Radar interference caused by confusion reflectors, such as CHAFF and ROPE ... [8] (3) CORNER REFLECTORS [10:61] (4) Aircraft altitude (in kilofeet). [1]

ANGLE OF ARRIVAL (AOA) - The angle between the negative of the propagation vector and a reference direction. [1] NOTE: If the reference direction is the course vector of a target, then the angle of arrival is the same as the TARGET ANGLE with respect to the radiating source.

ANODE - (1) An electrode through which current enters any conductor of a non-metallic class. Specifically, an electrolytic anode is an electrode at which negative ions are discharged, or positive ions are formed, or at which other oxidizing reactions occur. [3] (2) (ELECTRON (VACUUM) TUBE or valve) An electrode through which a principal stream of electrons leaves the inter-electrode space. [3]

ANONYMOUS REMAILER - An INTERNET computer service that launders the true identity of an e-mail sender by stripping away the message header before forwarding the message to the recipient, by padding the message to disguise its true length, or by encryption. [10:2815] Compare with PSEUDONYMOUS REMAILER.

ANTENNA - That part of a transmitting or receiving system that is designed to radiate or to receive electromagnetic waves. [3] NOTE: Antennas are characterized by coverage (non-directional or directional), Gain (generally in decibels), Frequency Range, POLARIZATION (linear or circular), BANDWIDTH (narrow or wide), and type. There are many types of antennas. The table below lists some antenna types. [10:2688]

ANTENNA TYPES
*Type*	*Typical Polarization*
Biconical	Vertical
Blade	Vertical or Linear
Cavity Backed Spiral	R & L Horizontal
Conical Spiral	Circular
Conical Spiral, 4-arm	Circular
Diffraction Plate	Linear
Dipole	Vertical
Horn	Linear
Horn with Polarizer	Circular
Helix, Axial Mode	Circular
Helix, Normal Mode	Horizontal
Linderblad	Circular
Log Periodic	Vertical or Horizontal
Loop	Horizontal
Parabolic Dish	Depends on feed
Periscope	Depends on feed
Phased Array	Depends on elements
Reflector	Depends on elements
Swastika	Horizontal
Whip	Vertical
Yagi	Horizontal

Antennas may also be classified into four types of fundamental operation as follows [10:2706]:

TYPES OF ANTENNA ELEMENTS
*Antenna Type*	*Properties*	Examples
Electrically Small	Very low directivity Low input resistance High input reactance Low radiation efficiency	Short dipole Small Loop
Resonant	Low to moderate gain Real input impedance Narrow bandwidth	Half-wave dipole Microstrip patch
Broadband	Low to moderate gain Constant gain with frequency Real input impedance Wide bandwidth	Spiral
Aperture	High gain Gain increases with frequency Moderate bandwidth	Horns Reflectors

For a technical discussion about antennas, click . [11.2] See also SPRAY-ON ANTENNA.

ANTENNA AUXILIARY SCAN-ON-RECEIVE-ONLY - An ECCM technique that uses an auxiliary non-scanning antenna and associated receiver that is boresighted with the transmit-and- receive antenna of a conical scan SORO (scan-on-receive-only) tracking system, to detect the ECM amplitude modulations on the receive signal and to use this to cancel the ECM modulation from the radar's received signal prior to angle processing within the radar. [8]

ANTI-AIR LASER - A NONLETHAL WARFARE weapon consisting of a vehicle, ship or aircraft-based laser cannon to ground pilots or force them to veer off or risk damage to pilot vision or to the aircraft windscreen, optics or targeting sensors. [10:2648] See also BLINDING LASER.

ANTI-AIR WARFARE (AAW) - A US Navy/US Marine Corps term used to indicate that action required to destroy or reduce to an acceptable level the enemy air and missile threat. It includes such measures as the use of interceptors, bombers, antiaircraft guns, surface-to-air and air-to-air missiles, ELECTRONIC COUNTERMEASURES, and destruction of the air or missile threat both before and after it has launched. Other measures which are taken to minimize the effects of hostile air action are COVER, concealment, dispersion, DECEPTION (including electronic) and mobility. [1] NOTE: "Bombers" in this definition implies their air-to-air capabilities and not air-to-ground destruction of enemy aircraft, which is a strike function.

ANTI-ARMOR MATERIALS - That category of MATERIALS TECHNOLOGY which addresses materials materials for projectiles used to defeat enemy armor, including various types of penetrators, sabots, shaped charge liners, and their launchers. Anti-armor materials include steel, titanium, ceramics, forged or explosively formed or rolled molybdenum, tantalum, tungsten, and depleted uranium (DU). [12]

ANTIJAM DATA LINKING - The establishing of data links which have the capability to counter jamming. []

ANTI-RADIATION MISSILE (ARM) DECOY - A miniature radar transmitter designed to protect radars in the field. The DECOY provides protection by emulating the transmission characteristics of the protected radar, thereby deceiving the incoming missile. [10:94]

ANTIREFLECTION OVERCOAT - A coating of material, such as poly-tetrafluoroethylene, which reduces the reflectance of a material at infrared wavelengths. [10:4] See also RADAR CAMOUFLAGE.

ANTISUBMARINE WARFARE (ASW) - (1) Operations conducted with the intention of denying the enemy the effective use of his submarines. [1] (2) The destruction or neutralization of enemy submarines. [2]

ANTISURFACE WARFARE (ASUW) - The destruction or neutralization of enemy surface combatants and merchant ships. Its aim is to deny the enemy the effective use of his surface warships and cargo carrying capacity. Synonymous with ANTI-SURFACE SHIP WARFARE. [2]

ANTI-SURVEILLANCE WARFARE - Military action intended to reduce the effectiveness of enemy surveillance operations. []

ANTI-TORPEDO TORPEDO (ATT) - A specialized small-diameter torpedo that tracks and destroys incoming underwater projectiles. The ATT uses digital signal processing and FUZZY LOGIC to identify, track and intercept incoming torpedoes running in a variety of attack patterns. [10:2875]

ANTI-TRACTION LUBRICANT A NONLETHAL WEAPON consisting of a lubricant applied to roadways which reduces friction of the surface and adversely affects the traction of vehicle wheels and tracks on the treated surfaces such as roads, runways, and tracks. [10:2754] A teflon-type environmentally neutral lubricant that make footholds or traction exceedingly difficult. In this application, the product can be used to deny access to areas or cover a unit's flank. [10:2857]

APPLIQUE - The Army's "Force XXI Battle Command Brigade-and-Below (FBCB²)" initiative to digitize the battlefield. [10:2740]

ARCHITECTURAL DESIGN - The process of defining a collection of hardware and software components and their interfaces to establish a framework for the development of a system. [10:33] NOTE: The architectural design process begins with the identification of functions which must be performed by the system in order to meet specified requirements. These functions are then allocated to software, hardware, or humans comprising the system. Differing allocation schemes become "architectural alternatives", and the chosen alternative results from consideration of various criteria and constraints, such as cost and manning. System inputs, outputs, internal and external interfaces, data sources and destinations, data stores, and transformation processes are all identified, diagrammed, and described in the architectural documentation.

AREA DENIAL SYSTEM (ADS) - Self-contained, semi-autonomous, long standoff munitions that can defend an area by defeating, disrupting, and delaying vehicles that enter its battlespace. [10:2724]

ARMOR MATERIALS - That category of MATERIALS TECHNOLOGY which addresses materials specifically designed to protect equipment and personnel from enemy threats. Armor materials include metals and related composites (e.g., titanium diboride), ceramics and related composites (e.g., crystal whiskers in a bonded matrix), organic fibers and composites (e.g., arrays of woven cloth), and layered combinations of these. [12]

ARPA LINCOLN C-BAND OBSERVABLE RADAR (ALCOR) - An Army-operated radar located on the Kwajalein Atoll in the western Pacific. It has two missions, Anti-Ballistic Missile (ABM) testing in support of the Western Space and Missile Center (WSMC) and space surveillance. ALCOR is a Near-Earth (NE) tracking radar. [10:2804] NOTE: ALCOR is unique because it is the only radar besides Haystack that can provide wideband Space Object Identification. [10:2804] ALCOR is one of the 25 sites worldwide of U.S. Army, Navy and Air Force operated ground-based radars and optical sensors composing the Space Surveillance Network. Two other radars are the ARPA Long-range Tracking and Identification Radar (ALTAIR) and the TRADEX (Target Resolution and Discrimination Experiment).

ARPA LONG-RANGE TRACKING AND IDENTIFICATION RADAR (ALTAIR) - A high-resolution radar located at Kwajalein Atoll in the western Pacific that provides precision metric, signature, and imaging for deep-space operations, satellite observations, strategic reentry missions, and multiple-intercept engagement tracking. ALTAIR is a Near-Earth (NE) and Deep Space (DS) tracking radar. ALTAIR has two missions: Anti-Ballistic Missile (ABM) testing in support of the Western Space and Missile Center (WSMC) and space surveillance. [10:2804] NOTE: ALTAIR is unique because it is the only radar in the Space Surveillance Network with an equatorial location. ALTAIR can track one third of the objects in the geosynchronous belt, more than 42,000 tracks per year. [10:2804] ALTAIR is one of the 25 sites worldwide of U.S. Army, Navy and Air Force operated ground-based radars and optical sensors composing the Space Surveillance Network. Two other radars are the ARPA Lincoln C-Band Observable Radar (ALCOR) and the TRADEX (Target Resolution and Discrimination Experiment).

ARRAY ANTENNA - An antenna comprised of a number of identical radiating elements in a regular arrangement and excited to obtain a prescribed radiation pattern. [3] See also PHASED ARRAY ANTENNA.

ARTIFICIAL EYELID - A MICROELECTROMECHANICAL device consisting of a surface covered by tiny shutters, ranging in size from about a millimeter to 50 micrometers. In the transparent state, the shutters are open, lik an open venetian blind. When a sensor detects light, the shutters quickly (about 100 microseconds) snap closed, presenting an opaque surface to the light. [10:2813] NOTE: The primary application of the artificial eyelid is to protect military pilots and equipment from disabling laser attacks. The artificial eyelid also has potential consumer applications, such as programmable sunglasses, or advanced camera lenses.

ARTILLERY DELIVERED ANTIPERSONNEL MINE (ADAM) - One of a number (e.g., 36) of mines contained in an artillery shell. When the mines fall from the disintegrating shell they release a tripwire-fired, pop-up fragmenting warhead. Each mine ejects several tripwires that, when disturbed, trigger the mine to jump four to eight feet in the air and spray shrapnel across a forty-foot area. [10:2735] NOTE: ADAM is in the class of SMART MINEs. ADAM has been adapted for hand-emplacement and has evolved into the Pursuit Deterrent Munition (PDM)

ASPHALT ABLATION - A ballistic missile countermeasure involving deployment of an asphalt cloud in the exoatmosphere in front of an incoming missile. The asphalt particles cling to the warhead, and during re-entry the asphalt ignites and ablates unevenly, degrading the missile's accuracy. [8*]

ASROC - Acronym for Anti-Submarine Rocket. ASROC is a weapon consisting of a rocket booster used to deliver a payload torpedo or depth-charge over an extended distance, providing long-distance ASW capability. When launched, the ASROC proceeds to the area of the target, releases the weapon which deploys a parachute to slow the weapon before entering the water. After entering the water, the weapon begins its programmed target acquisition maneuvers. [] NOTE: The ASROC launcher is usually trainable in azimuth and elevation. If the launcher is fixed in the vertical plane, then the weapon is a VERTICAL-LAUNCH ASROC (VLA).

ASSEMBLY LANGUAGE - A programming language that corresponds closely to the instruction set of a given computer, allows symbolic naming of operations and addresses, and usually results in a one-to-one translation of program instructions into MACHINE LANGUAGE. [3]

ASYMMETRICAL MILITARY FORCE - A military force that does not attempt to match the size of that of an adversary, but is designed to exploit the weakness of the larger force. The assymetrical military force would be small, mobile, elusive, efficient, inventive and high-tech. []

ASYMMETRIC WARFARE - (1) Warfare between dissimilar forces. (2) War between two sides with dissimilar goals. (3) Warfare in which new technology is used to defeat the superior with the inferior. (4) Warfare which encompasses anything - strategy, tactics, weapons, personnel - that alters the battlefield to negate one side or the other's advantage. [] NOTE: Asymmetric warfare has been described as "not fighting fair". There are many "definitions" of asymmetric warfare, as the forgoing suggests. These descriptions come from the web site: http://www.amsc.belvoir.army.mil/asymmetric_warfare.htm.

ATMOSPHERIC INFRARED SOUNDER (AIRS) - A sensor (to be launched in late 2000) that can measure Earth's air temperatures from space with great precision, allowing accurate weather predictions. The AIRS will read atmospheric temperatures to within one degree Celsius in 1-kilometer layers of altitude in the Earth's lower atmosphere. AIR's high-resolution spectrometer will sample precisely the Earth's atmosphere from the ground up to 30 miles. [10:2805]

AUTOMATIC GAIN CONTROL (AGC) - A process or means by which gain is automatically adjusted in a specified manner as a function of input or other specified parameters. [3]

AUTOMATIC LOCAL OSCILLATOR TUNING - An ECCM technique wherein the radar's local oscillator is tuned either side of its normal setting to see if the target signal ECHO can be more easily detected in a JAMMING environment. [8]

AUTOMATIC VIDEO NOISE LIMITING - An ECCM technique where the NOISE level out of the radar receiver is maintained constant by a closed-loop feedback system that varies the gain of the video amplifier. [8]

AUTONOMIC HEALING - The automatic dispersing of a series of microspheres that contain a healing agent and a catalyst in a polymeric composite. When a crack propagates in the treated material, stress causes the closest spheres to break open and release the healing agent and catalyst which generate a chemical reaction to polymerize and heal the crack through capillary action, bonding the crack faces to each other. [10:2904] Also called MICROENCAPSULATED HEALING AGENT, HEALING AGENT.

AUTONOMOUS DECOY - A self- propelled platform which emulates a protected unit, for example, a self-propelled surface acoustic DECOY playing a tape recording of ship sounds. [4:23]

AUTONOMOUS TARGET RECOGNITION (ATR) - The ability of a weapon to locate and engage a target without data updates or guidance from external sources. ATR involves automated high speed signal or imaging processing, rapid data base management and high fidelity classification and correlation. Contrast with MAN-IN-THE-LOOP SYSTEMS. See also BRILLIANT AMMUNITION, SMART WEAPON. [10:31] NOTE: There are three primary components of ATR: algorithms, processors, and sensor technology.

AVATAR - In a VIRTUAL ENVIRONMENT, a three-dimensional image (which may also include live video) that serves as a stand-in for the person who controls it. Its motions, gestures, and speech may be derived from the user's voice, keyboard, or other input device. More generally, an avatar is a representation of any object functioning in a virtual world, and so its meaning may cover graphical representations of BOTs and AGENTs. [10:2595]