5/19/2023 0 Comments Network radarThe radar measures the location of the target in range and angular direction. Signals that are not of interest might be echoes from the ground or rain, which can mask and interfere with the detection of the desired echo from the aircraft. For example, a signal of interest might be the echo from an aircraft. Since most radar systems do not transmit and receive at the same time, a single antenna is often used on a time-shared basis for both transmitting and receiving.Ī receiver attached to the output element of the antenna extracts the desired reflected signals and (ideally) rejects those that are of no interest. When a target is illuminated by the beam, it intercepts some of the radiated energy and reflects a portion back toward the radar system. The narrow antenna beam scans a region where targets are expected. Radar typically involves the radiating of a narrow beam of electromagnetic energy into space from an antenna ( see the figure). At the same time, radar has found an increasing number of important civilian applications, notably air traffic control, weather observation, remote sensing of the environment, aircraft and ship navigation, speed measurement for industrial applications and for law enforcement, space surveillance, and planetary observation. It is still widely employed by the armed forces, where many technological advances have originated. Radar underwent rapid development during the 1930s and ’40s to meet the needs of the military. The circuit components and other hardware of radar systems vary with the frequency used, and systems range in size from those small enough to fit in the palm of the hand to those so enormous that they would fill several football fields. It has, however, been used at lower frequencies for long-range applications (frequencies as low as several megahertz, which is the HF, or shortwave, band) and at optical and infrared frequencies (those of laser radar, or lidar). It typically operates in the microwave region of the electromagnetic spectrum-measured in hertz (cycles per second), at frequencies extending from about 400 megahertz (MHz) to 40 gigahertz (GHz). Radar is an “active” sensing device in that it has its own source of illumination (a transmitter) for locating targets. What distinguishes radar from optical and infrared sensing devices is its ability to detect faraway objects under adverse weather conditions and to determine their range, or distance, with precision. Besides determining the presence, location, and velocity of such objects, radar can sometimes obtain their size and shape as well. The targets may be aircraft, ships, spacecraft, automotive vehicles, and astronomical bodies, or even birds, insects, and rain. It operates by transmitting electromagnetic energy toward objects, commonly referred to as targets, and observing the echoes returned from them. Radar, electromagnetic sensor used for detecting, locating, tracking, and recognizing objects of various kinds at considerable distances. Learn how a radar works See all videos for this article ![]() SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today. ![]()
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