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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 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.
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.
The radar mile is the time it takes for a radar pulse to travel one nautical mile, reflect off a target, and return to the radar antenna. Since a nautical mile is defined as 1,852 m, then dividing this distance by the speed of light (299,792,458 m/s), and then multiplying the result by 2 yields a result of 12.36 μs in duration.
The radar measures the distance to the reflector by measuring the time of the round trip from emission of a pulse to reception, dividing this by two, and then multiplying by the speed of light. To be accepted, the received pulse has to lie within a period of time called the range gate .
Definition of angles in the vertical plane of SLAR Geometry of an SLAR SLAR radar at ILA Berlin Air Show. 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.
To plot any dot from its spherical coordinates (r, θ, φ), where θ is inclination, the user would: move r units from the origin in the zenith reference direction (z-axis); then rotate by the amount of the azimuth angle (φ) about the origin from the designated azimuth reference direction, (i.e., either the x– or y–axis, see Definition ...
A drawback of the multi-beam mode is the presence of blind ranges across the swath, as the radar cannot receive while it is transmitting. [ 12 ] [ 13 ] Several innovative techniques using multiple receive apertures (‘Rx’) have been suggested to overcome the inherent limitations of conventional SAR to perform HRWS imaging.