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Side Looking Airborne Radar
Side-looking airborne radar (SLAR) is an aircraft, or satellite-mounted imaging radar pointing perpendicular to the direction of flight (hence ''side-looking''). A Squint (antenna), squinted (nonperpendicular) mode is also possible. SLAR can be fitted with a standard antenna (real aperture radar) or an antenna using Synthetic aperture radar, synthetic aperture. The platform of the radar moves in direction of the x-axis. The radar "looks" with the looking angle ''θ'' (or so called off-nadir angle). The angle ''α'' between x-axis and the line of sight (LOS) is called cone angle, the angle ''φ'' between the x-axis and the projection of the line of sight to the (x; y)-plane is called azimuth angle. Cone- and azimuth angle are related by cos''α'' = cos''φ'' ∙ cos''ε''. On the earth surface the wave comes in at the (nominal ellipsoidal) incident angle ''β'' with respect to the vertical axis at this point. (In some publications the incident angle is denomin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ILA 2024, Schoenefeld (ILA44493)
Ila or ILA may refer to: Government * Ila Detention and Security Prison, a prison in Bærum, Norway * Israel Land Administration * Israel Land Authority, the successor agency to the Israel Land Administration Organizations * Idaho Library Association * Illinois Library Association * Immersive Light and Art, an arts organisation in Adelaide, Australia * Indian Laser Association * Indian Library Association * Institute of Landscape Architects, in UK * Institute for Legislative Action (NRA-ILA), political lobbying arm of the National Rifle Association of America * International Law Association * International Linguistic Association * International Longevity Alliance, an international nonprofit organization promoting life extension * International Longshoremen's Association, North American labor union * Iowa Library Association Places * Ila, China, former name of Huiyuan in Xinjiang * Ila, Georgia, a community in United States * Ila, Osun, a local government area in Nigeria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imaging Radar
Imaging radar is an application of radar which is used to create two-dimensional images, typically of landscapes. Imaging radar provides its light to illuminate an area on the ground and take a picture at radio wavelengths. It uses an antenna and digital computer storage to record its images. In a radar image, one can see only the energy that was reflected back towards the radar antenna. The radar moves along a flight path and the area illuminated by the radar, or footprint, is moved along the surface in a swath, building the image as it does so. Digital radar images are composed of many dots. Each pixel in the radar image represents the radar backscatter for that area on the ground (terrain return): brighter areas represent high backscatter, darker areas represents low backscatter. The traditional application of radar is to Radar display, display the position and motion of typically highly reflective objects (such as aircraft or ships) by sending out a radiowave signal, and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squint (antenna)
In a phased array or slotted waveguide antenna, squint refers to the angle that the transmission is offset from the normal of the plane of the antenna. In simple terms, it is the change in the beam direction as a function of operating frequency, polarization, or orientation. It is an important phenomenon that can limit the bandwidth in phased array antenna systems. This deflection can be caused by: ;Signal frequency :Signals in a waveguide travel at a speed that varies with frequency and the dimensions of the waveguide. In a phased array or slotted waveguide antenna, the signal is designed to reach the outputs in a given phase relationship. This can be accomplished for any single frequency by properly adjusting the length of each waveguide so the signals arrive in-phase. However, if a different frequency is sent into the feeds, they will arrive at the ends at different times, the phase relationship will not be maintained, and squint will result. Frequency-dependant phase shift ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthetic Aperture Radar
Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or 3D reconstruction, three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide finer spatial resolution than conventional stationary beam-scanning radars. SAR is typically mounted on a moving platform, such as an aircraft or spacecraft, and has its origins in an advanced form of side looking airborne radar (SLAR). The distance the SAR device travels over a target during the period when the target scene is illuminated creates the large ''synthetic'' antenna aperture (the ''size'' of the antenna). Typically, the larger the aperture, the higher the image resolution will be, regardless of whether the aperture is physical (a large antenna) or synthetic (a moving antenna) – this allows SAR to create high-resolution images with comparatively small physical antennas. For a fixed antenna size and orientation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nadir
The nadir is the direction pointing directly ''below'' a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface. The direction opposite of the nadir is the zenith. Etymology Although it entered English via other European languages, the word “nadir” is ultimately an Arabic loanword. It comes from the Arabic word “nazir”, meaning “opposite to”. More specifically, it originated from the Arabic phrase “nazir as-samt”, meaning “ heopposite direction”. Hebrew (whether ancient or modern) is a related language to Arabic, as they are both Semitic languages. Hebrew also has a word “nadir” (נדיר), but with a somewhat different meaning: it is an adjective meaning “rare”. However, the same word also has a specialized usage to match its meaning in other languages like English. Definitions Space science Since the concept of ''being below'' is itself somewhat vague, scientists define ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse Compression
Pulse compression is a signal processing technique commonly used by radar, sonar and Ultrasound, echography to either increase the range angular resolution, resolution when pulse length is constrained or increase the Signal-to-noise ratio, signal to noise ratio when the peak power and the Bandwidth_(signal_processing), bandwidth (or equivalently range resolution) of the transmitted signal are constrained. This is achieved by modulation, modulating the transmitted pulse and then Cross-correlation, correlating the received signal with the transmitted pulse. Simple pulse Signal description The ideal model for the simplest, and historically first type of signals a pulse radar or sonar can transmit is a truncated sinusoidal pulse (also called a CW --carrier wave-- pulse), of amplitude A and carrier frequency, f_0, truncated by a rectangular function of width, T. The pulse is transmitted periodically, but that is not the main topic of this article; we will consider only a single ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar Imaging
Radar is a system that uses radio waves to determine the distance (''ranging''), direction (geometry), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track aircraft, Marine radar, ships, spacecraft, guided missiles, motor vehicles, map Weather radar, weather formations, and terrain-following radar, terrain. The term ''RADAR'' was coined in 1940 by the United States Navy as an acronym and initialism, acronym for "radio detection and ranging". The term ''radar'' has since entered English and other languages as an wikt:anacronym, anacronym, a common noun, Acronym#All-caps style, losing all capitalization. A radar system consists of a transmitter producing electromagnetic waves in the radio spectrum, radio or microwave domain, a transmitting antenna (radio), antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a radio receiver, receiver an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Radars
An aircraft ( aircraft) is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, direct downward thrust from its engines. Common examples of aircraft include airplanes, rotorcraft (including helicopters), airships (including blimps), gliders, paramotors, and hot air balloons. Part 1 (Definitions and Abbreviations) of Subchapter A of Chapter I of Title 14 of the U. S. Code of Federal Regulations states that aircraft "means a device that is used or intended to be used for flight in the air." The human activity that surrounds aircraft is called ''aviation''. The science of aviation, including designing and building aircraft, is called ''aeronautics.'' Crewed aircraft are flown by an onboard pilot, whereas unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Aircraft may be classified by different criteria, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
