Säteilykuvion

Säteilykuvion, often translated as radiation pattern or antenna pattern, describes the directional dependence of the radiation emitted or received by an antenna. It is a graphical representation that shows how the power is distributed in space around the antenna. Typically, this is visualized in two or three dimensions. The pattern is usually expressed in terms of the electric field strength, power density, or intensity.

A radiation pattern is characterized by several key features. The main lobe is the direction of maximum radiation. Side lobes are smaller lobes that radiate in directions other than the main lobe. Nulls are directions where the radiation is minimal or zero. The beamwidth is the angular width of the main lobe, often measured at the half-power points.

Understanding the radiation pattern is crucial for antenna design and application. It helps determine the antenna's coverage area, its ability to reject interference from unwanted directions, and its suitability for specific communication systems. For example, a highly directional antenna with a narrow beamwidth is suitable for point-to-point communication, while an antenna with a broad pattern might be used for broadcasting.

Radiation patterns can be measured experimentally or calculated theoretically. Measurements are often performed in an anechoic chamber to avoid reflections. Theoretical calculations involve solving Maxwell's equations for the specific antenna geometry and excitation. The patterns are typically normalized so that the maximum radiation is represented as a specific value, often 0 dB.