Meaning
Characterizing spatial power distribution describes the angular variation of radiated energy at distances sufficiently removed from an antenna where signal geometry stabilizes into plane waves. Wireless modules rely on far field beam pattern measurement to evaluate main lobe gain, beamwidth, side lobe suppression ratios, and front-to-back ratios across target frequency bands. Measurements taken in this Fraunhofer region remain independent of distance, allowing direct calculation of effective isotropic radiated power and spatial coverage profiles.
The scope covers the far field region extending outward from the Rayleigh distance, excluding reactive near field and radiating near field phenomena.
Angular Distribution
Radiation intensity varies continuously across spherical coordinates surrounding the antenna assembly. Main beam directional steering focuses power toward intended receiver targets while minimizing off-axis radiation. Side lobe levels must remain below specified power limits to prevent interference with adjacent channel receivers.
Pattern measurements confirm main lobe beamwidth matching system link budget requirements.
Distance Threshold
Fraunhofer distance calculations establish the minimum measurement radius based on antenna dimension and operating wavelength. Operating at two times the square of the maximum antenna dimension divided by wavelength guarantees planar wave conditions. Testing closer than this threshold introduces phase errors that distort measured nulls and peak power positions.
Antenna test engineers select range distances that satisfy this mathematical criterion.
Antenna Architecture
Patch arrays, dish reflectors, and integrated module antennas display distinct directional shapes dictated by their physical layout. Element spacing, ground plane dimensions, and dielectric substrate parameters shape the main beam profile. Phased array architectures manipulate phase across individual elements to sweep the beam dynamically across spatial sectors.
Production testing verifies pattern shape consistency across manufacturing lots.
