Meaning
Electromagnetic radiation distributions characterize the wireless behavior of an antenna at a distance where the wave front is effectively planar. The far field pattern describes how a wireless device distributes its transmitted energy across different angles in three-dimensional space. This profile determines the coverage area, directivity, and peak gain of the integrated radio system.
It is measured in specialized chambers where the distance from the source exceeds the Fraunhofer boundary.
Spatial Coverage
Angular distribution measurements reveal the direction of maximum signal strength. Analysis of the far field pattern allows RF engineers to optimize the placement of the antenna within the device enclosure. Mobile devices require a relatively omnidirectional pattern to maintain connectivity during movement, while point-to-point links use narrow beams.
Boundary Condition
Distance formulas define where the radiating near-field transitions into the propagation region. Calculating the far field pattern requires a separation distance proportional to the square of the antenna dimension divided by the wavelength. Inside this boundary, the reactive field dominates and does not represent the real-world performance of the transmitter.
Antenna Integration
Enclosure materials and nearby circuit components alter the directional characteristics of the transmitter. Changes in the far field pattern occur when an antenna module is mounted next to batteries or metal brackets.
