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Tundra and Molniya orbits are used to provide high-latitude users with higher elevation angles than a geostationary orbit.This is desirable as broadcasting to these latitudes from a geostationary orbit (above the Earth's equator) requires considerable power due to the low elevation angles, and the extra distance and atmospheric attenuation that comes with it.
As a GNSS satellite rises or sets, the elevation angle changes; the direct and reflected signals will generate an interference pattern. The frequency of this interference pattern can be used to extract the height of the antenna above the planar surface, the reflector height.
For a satellite orbiting the Earth directly above the Equator, the plane of the satellite's orbit is the same as the Earth's equatorial plane, and the satellite's orbital inclination is 0°. The general case for a circular orbit is that it is tilted, spending half an orbit over the northern hemisphere and half over the southern.
A Molniya orbit (Russian: Молния, IPA: [ˈmolnʲɪjə] ⓘ, "Lightning") is a type of satellite orbit designed to provide communications and remote sensing coverage over high latitudes. It is a highly elliptical orbit with an inclination of 63.4 degrees , an argument of perigee of 270 degrees, and an orbital period of approximately half a ...
Short wave transmitters want a somewhat higher elevation angle in the vertical plane to encourage skywave propagation, which would refract or reflect radio waves off the ionosphere and back to the ground at a great distance from the transmitter.
The value of a solar beta angle for a satellite in Earth orbit can be found using the equation = [ + ()] where is the ecliptic true solar longitude, is the right ascension of ascending node (RAAN), is the orbit's inclination, and is the obliquity of the ecliptic (approximately 23.45 degrees for Earth at present).
The radar antenna sends pulses while rotating 360 degrees around the radar site at a fixed elevation angle. It can then change angle or repeat at the same angle according to the need. Return echoes from targets are received by the antenna and processed by the receiver and the most direct display of those data is the PPI.
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 cosα = cosφ ∙ cosε.