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Low-probability-of-intercept Radar
A low-probability-of-intercept radar (LPIR) is a radar employing measures to avoid detection by passive radar detection equipment (such as a radar warning receiver (RWR), or electronic support receiver) while it is searching for a target or engaged in target tracking. This characteristic is desirable in a radar because it allows finding and tracking an opponent without alerting them to the radar's presence. This also protects the radar installation from anti-radiation missiles (ARMs). LPI measures include: *Power management and high duty cycle, meaning the transmitter is on most of the time (long integration times) *Wide bandwidth (or Ultra-wideband) *Frequency Agility, and frequency selection *Advanced/irregular scan patterns *Coded pulses (coherent detection) *High processing gain *Low sidelobe antennas Rationale Radar systems work by sending out a signal and then listening for its echo off distant objects. Each of these paths, to and from the target, is subject to the inverse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor vehicles, Weather radar, weather formations, and terrain-following radar, terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio spectrum, radio or microwaves domain, a transmitting antenna (radio), antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a radio receiver, receiver and Data processing system, processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in the period before and during World War II. A key development was the ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Hopping
Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both transmitter and receiver. FHSS is used to avoid interference, to prevent eavesdropping, and to enable code-division multiple access (CDMA) communications. The available frequency band is divided into smaller sub-bands. Signals rapidly change ("hop") their carrier frequencies among the center frequencies of these sub-bands in a predetermined order. Interference at a specific frequency will affect the signal only during a short interval. FHSS offers four main advantages over a fixed-frequency transmission: # FHSS signals are highly resistant to narrowband interference because the signal hops to a different frequency band. # Signals are difficult to intercept if the frequency-hopping pattern is not known. # Jamming is also difficult if the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AN/APG-79
The AN/APG-79 is a variant of an active electronically scanned array (AESA) radar developed for the United States Navy's Boeing F/A-18E/F Super Hornet and Boeing EA-18G Growler aircraft, providing a high level of aircrew situational awareness. The beam of the AESA radar provides fast track updates and multi-target tracking capability. The APG-79 AESA uses transmit/receive (TR) modules populated with Gallium arsenide Monolithic microwave integrated circuits. In the F/A-18E/F, the radar is installed in a slide-out nose rack to facilitate maintenance. The APG-79 features an entirely solid-state antenna construction, which improves reliability, durability, and reduces the cost compared to a traditional radar system. The radar has a range of up to 150 km (80 nm) and multi-target tracking capabilities. The APG-79 is compatible with current F/A-18 weapon loads and enables aircrew to fire weapons such as the AIM-120 AMRAAM, and simultaneously guide several missiles to several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-22 Raptor
The Lockheed Martin F-22 Raptor is an American single-seat, twin-engine, all-weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). As the result of the USAF's Advanced Tactical Fighter (ATF) program, the aircraft was designed as an air superiority fighter, but also has ground attack, electronic warfare, and signals intelligence capabilities. The prime contractor, Lockheed Martin, built most of the F-22's airframe and weapons systems and conducted final assembly, while Boeing provided the wings, aft fuselage, avionics integration, and training systems. The aircraft first flew in 1997 and was variously designated F-22 and F/A-22 before it formally entered service in December 2005 as the F-22A. Although the USAF had originally planned to buy a total of 750 ATFs, the program was cut to 187 operational aircraft in 2009 due to high costs, a lack of air-to-air missions due to the focus on counterinsurgency operations at the time of production, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northrop Grumman
Northrop Grumman Corporation is an American multinational aerospace and defense technology company. With 90,000 employees and an annual revenue in excess of $30 billion, it is one of the world's largest weapons manufacturers and military technology providers. The firm ranks on the 2022 ''Fortune'' 500 list of America's largest corporations. Northrop Grumman and its industry partners have won the Collier Trophy eight times, most recently for developing the X-47B, the first unmanned, autonomous air system to operate from an aircraft carrier. Northrop Grumman currently leads the development of the B-21 Raider, a long-range, stealth strategic bomber that can drop conventional and nuclear weapons; it will replace Northrop's own B-2 Spirit, the world's only known stealth bomber. Among its other current projects are development and production of the James Webb Space Telescope, an orbiting observatory launched in 2021, and production of the solid rocket boosters for NASA's Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AN/APG-77
The AN/APG-77 is a multifunction low probability of intercept radar installed on the F-22 Raptor fighter aircraft. The radar was designed and initially built by Westinghouse and Texas Instruments, and production continued with their respective successors Northrop Grumman and Raytheon after acquisition. It is a solid-state, active electronically scanned array (AESA) radar. Composed of 1956 transmit/receive modules, each about the size of a gum stick, it can perform a near-instantaneous beam steering (in the order of tens of nanoseconds). The APG-77 provides 120° field of view in azimuth and elevation,. APG-77 has an operating range of while unconfirmed sources suggest an operating range of , against a target. A range of 400 km or more, with the APG-77v1 with newer GaAs modules is believed to be possible while using more narrow beams. More than 100 APG-77 AESA radars have been produced to date by Northrop Grumman, and much of the technology developed for the APG-77 is b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SA-10 Grumble
The S-300 (NATO reporting name SA-10 Grumble) is a series of long range surface-to-air missile systems developed and operated by the former Soviet Union, now fielded by the militaries of Russia and Ukraine as well as several other former Eastern Bloc countries. It was produced by NPO Almaz, based on the initial S-300P version. The S-300 system was developed to defend against air raids and cruise missiles for the Soviet Air Defence Forces. Subsequent variations were also developed to be able to intercept ballistic missiles. The S-300 system was first deployed by the Soviet Union in 1979, designed for the air defence of large industrial and administrative facilities, military bases and control of airspace against enemy strike aircraft. During the Russian invasion of Ukraine in 2022, military analysts have stated that Russia has modified a number of systems to perform surface-to-surface strikes. The system is fully automated, though manual observation and operation are also p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F/A-18E/F Super Hornet
The Boeing F/A-18E and F/A-18F Super Hornet are twin-engine, carrier-capable, multirole fighter aircraft variants based on the McDonnell Douglas F/A-18 Hornet. The F/A-18E single-seat and F/A-18F tandem-seat variants are larger and more advanced derivatives of the F/A-18C and D Hornet. The Super Hornet has an internal 20 mm M61 rotary cannon and can carry air-to-air missiles and air-to-surface weapons. Additional fuel can be carried in up to five external fuel tanks and the aircraft can be configured as an airborne tanker by adding an external air-to-air refueling system. Designed and initially produced by McDonnell Douglas, the Super Hornet first flew in 1995. Low-rate production began in early 1997 with full-rate production starting in September 1997, after the merger of McDonnell Douglas and Boeing the previous month. The Super Hornet entered fleet service with the United States Navy in 1999, replacing the Grumman F-14 Tomcat, which was retired in 2006; the Sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Electronically Scanned Array
An active electronically scanned array (AESA) is a type of phased array antenna, which is a computer-controlled array antenna in which the beam of radio waves can be electronically steered to point in different directions without moving the antenna. In the AESA, each antenna element is connected to a small solid-state transmit/receive module (TRM) under the control of a computer, which performs the functions of a transmitter and/or receiver for the antenna. This contrasts with a passive electronically scanned array (PESA), in which all the antenna elements are connected to a single transmitter and/or receiver through phase shifters under the control of the computer. AESA's main use is in radar, and these are known as active phased array radar (APAR). The AESA is a more advanced, sophisticated, second-generation of the original PESA phased array technology. PESAs can only emit a single beam of radio waves at a single frequency at a time. The PESA must utilize a Butler matrix ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar Jamming And Deception
Radar jamming and deception is a form of electronic countermeasures that intentionally sends out radio frequency signals to interfere with the operation of radar by saturating its receiver with noise or false information. Concepts that blanket the radar with signals so its display cannot be read are normally known as jamming, while systems that produce confusing or contradictory signals are known as deception, but it is also common for all such systems to be referred to as jamming. There are two general classes of radar jamming, mechanical and electronic. Mechanical jamming entails reflecting enemy radio signals in various ways to provide false or misleading target signals to the radar operator. Electronic jamming works by transmitting additional radio signals towards enemy receivers, making it difficult to detect real target signals, or take advantage of known behaviors of automated systems like radar lock-on to confuse the system. Various counter-countermeasures can sometimes hel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Side Lobe
In antenna engineering, sidelobes are the lobes (local maxima) of the far field radiation pattern of an antenna or other radiation source, that are not the ''main lobe''. The radiation pattern of most antennas shows a pattern of "''lobes''" at various angles, directions where the radiated signal strength reaches a maximum, separated by "''nulls''", angles at which the radiated signal strength falls to zero. This can be viewed as the diffraction pattern of the antenna. In a directional antenna in which the objective is to emit the radio waves in one direction, the lobe in that direction is designed to have a larger field strength than the others; this is the "''main lobe''". The other lobes are called "''sidelobes''", and usually represent unwanted radiation in undesired directions. The sidelobe directly behind the main lobe is called the back lobe. The longer the antenna relative to the radio wavelength, the more lobes its radiation pattern has. In transmitting antennas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
