What is NFTF?
NFTF (Near-Field to Far-Field Transform) is an OTA test methodology that measures the electromagnetic field radiated by a device in the near-field region and then uses mathematical transformations to compute the equivalent far-field radiation pattern. NFTF is one of the 3GPP-approved indirect far-field (IFF) methods for 5G NR testing and is particularly valuable at mmWave frequencies where direct far-field measurement would require impractical distances. NFTF can provide complete 3D pattern information including amplitude, phase, and polarization.
How Does NFTF Work?
In NFTF testing, a probe antenna scans the DUT’s radiated field on a defined surface — planar, cylindrical, or spherical — in the near-field region (within a few wavelengths of the DUT). At each scan point, both amplitude and phase are measured for each polarization. A mathematical transform (typically a 2D Fourier transform for planar scanning, or spherical harmonic expansion for spherical scanning) converts the sampled near-field data into the equivalent far-field pattern. Spherical NFTF provides the most complete characterization but requires the most scan points. Planar NFTF is faster but captures only a limited angular range. The quality of the result depends on scan resolution, probe correction, and positional accuracy.
Use Cases
5G NR FR2 device and antenna OTA testing, phased array antenna development and characterization, massive MIMO panel verification, antenna design validation, and production antenna pattern measurement for quality control.
3GPP / Standards Reference
3GPP TR 38.810 (Study on test methods for NR), 3GPP TS 38.141-2 (NR BS OTA conformance testing), IEEE Std 1720 (Near-field antenna measurements)
Related Terms
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