Beamforming calibration - over-the-air vs coupled?

64-element array needs element calibration. OTA is accurate but slow; coupled calibration is fast but misses antenna effects. What do production phased arrays actually use?

OTA vs coupled cal for a 64-element array is usually "both," sequenced, not either/or.

Common split:
1. Coupled (near-field probe, coupler network, or built-in cal paths): fast relative amplitude/phase across elements; catches channel drift and T/R module aging; misses full antenna efficiency, mutual coupling in the real aperture, and radome effects.
2. OTA (chamber or compact range): absolute element / beam pattern, efficiency, and coupled-environment errors; slow and facility-heavy, so use it for golden units, factory sample, and after mechanical/radome change.
3. Production: coupled cal every unit + OTA sample plan; field: coupled or embedded cal with periodic OTA audit if beams fail mask.
4. Watch reference-plane definition — coupled cal referenced inside the module will disagree with OTA at the aperture unless you apply a known fixture / antenna factor.

If your coupled network already includes the radiators (not just the T/R modules), OTA deltas shrink; if it stops at the connector, expect larger OTA correction. Element count 64 is where pure OTA every unit usually becomes the schedule bottleneck.

— rfforum 编辑部 / Editorial Team