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Rho-Theta methodology is a key component in Area Navigation (RNAV). [1] The term "Rho-Theta" consists of the two Greek letters corresponding to Rho and Theta: [2] [3] [4] Rho (Greek ρ) as a synonym for distance measurement, e.g. Rho would be the equivalent to the English abbreviation "R" for Range
The radar horizon is a critical area of performance for aircraft detection systems, defined by the distance at which the radar beam rises enough above the Earth's surface to make detection of a target at the lowest level possible.
Monostatic radar cross section (RCS) of a perfectly conducting metal sphere as a function of frequency (calculated by Mie theory). In the low-frequency Rayleigh scattering limit, where the circumference is less than wavelength, the normalized RCS is σ π R 2 ∼ 9 ( k R ) 4 {\displaystyle {\tfrac {\sigma }{\pi R^{2}}}\sim 9(kR)^{4}} .
The resolution of any radar depends on the width of the beam and the range to the target. For example; a radar with 1 degree beam width and a target at 120 km (75 mi) range will show the target as 2 km (1.2 mi) wide. To produce a 1-degree beam at the most common frequencies, an antenna 1.5 kilometres (0.93 miles) wide is required.
Diagram of AN/SPY-3 vertical electronic pencil beam radar conex projections. X band functionality (8 to 12 GHz frequency range) is optimal for minimizing low-altitude propagation effects, narrow beam width for best tracking accuracy, wide frequency bandwidth for effective target discrimination, and the target illumination for SM-2 and Evolved Sea Sparrow Missiles (ESSM).
Side-looking airborne radar (SLAR) is an aircraft, [1] or satellite-mounted imaging radar pointing perpendicular to the direction of flight (hence side-looking). [2] A squinted (nonperpendicular) mode is also possible. SLAR can be fitted with a standard antenna (real aperture radar) or an antenna using synthetic aperture.
Beam riding is one of the simplest methods of missile guidance using a radar. It was widely used for surface-to-air missiles in the post-World War II era for this reason. An early example was the British Brakemine, first tested in 1944, as was the first commercially available SAM, the Oerlikon Contraves RSA.
The AN/FPS-117 is an L-band active electronically scanned array (AESA) 3-dimensional air search radar first produced by GE Aerospace in 1980 and now part of Lockheed Martin. [1] [2] The system offers instrumented detection at ranges on the order of 200 to 250 nautical miles (370 to 460 km; 230 to 290 mi) and has a wide variety of interference and clutter rejection systems.