What is CATR?
CATR (Compact Antenna Test Range) is a specialized test facility used to measure antenna radiation patterns and RF performance of wireless devices under controlled far-field conditions within a compact indoor environment. The CATR uses a parabolic reflector or shaped reflector to transform a spherical wave from a feed antenna into a planar wave front, simulating far-field conditions at a fraction of the distance normally required. CATR is one of the 3GPP-approved indirect far-field (IFF) test methods for 5G NR device OTA testing, particularly critical at mmWave frequencies.
How Does CATR Work?
Inside a CATR chamber, a feed antenna illuminates a large precision-machined parabolic reflector. The reflector collimates the incoming spherical wave into a plane wave across a defined quiet zone — the area where the device under test (DUT) is positioned. The DUT is mounted on a positioner that rotates in azimuth and elevation to capture the full 3D radiation pattern. The quiet zone must maintain amplitude ripple below ±0.5 dB and phase variation below ±5° to ensure measurement accuracy. At mmWave frequencies (FR2), CATR provides a practical alternative to direct far-field testing which would require impractically long distances.
Use Cases
5G NR FR2 (mmWave) device OTA conformance testing, massive MIMO base station antenna pattern characterisation, phased array antenna verification, EIRP and TRP measurements for device certification, and radar cross-section measurements.
3GPP / Standards Reference
3GPP TS 38.141-2 (NR BS conformance testing — radiated), 3GPP TR 38.810 (Study on test methods for NR), CTIA OTA Test Plan
Related Terms
Related Terms
OTA | AAT | NFTF | DFF | Fronthaul
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
