Cosecans² diagram
Antennas with a Cosecans² diagram are special antenna designs that are particularly suitable for circular search radar devices . They allow a situation-adapted radiation distribution and come closer to the idea of ideal spatial scanning than, for example, antennas with a fan diagram .
In the ideal case, a cosec² characteristic ensures that a flight target, which is moving towards or away from the antenna at a constant height, delivers an echo with constant amplitude at the receiver input.
Inverted Cosecans² diagram
If targets are to be located on the ground or on the water, an Inverse Cosecans² antenna is usually used. This is a Cosecans² antenna whose Cosecans² antenna diagram is rotated by 180 ° (i.e. turned upside down). As a result, a vertical antenna pattern nestled against the earth's surface is achieved, which causes a preferred view of objects on the ground, while high-flying targets are ignored. These antennas are used by airfield surveillance radars , coastal protection radar, and some marine radars.
Stacked beam cosecans² diagram
With a Stacked Beam Cosecans² antenna , a reflector is illuminated by several primary radiators placed one above the other. Each primary radiator is already directed. If the transmission power is distributed unevenly over the individual radiators, the antenna characteristic in the sum of the individual diagrams approximates the cosecans² characteristic.
If a separate receiving channel is also used for each primary radiator, an altitude assignment can also take place, since individual flight targets can now be assigned to individual beams.
See also
Web links
- Radar basics - u. a. Derivation of the term "Cosecans²"