B.2.5 Near field to far field transform (NFTF)

38.508-13GPP5GSPart 1: Common test environmentRelease 17TSUser Equipment (UE) conformance specification

B.2.5.1 Description

The NFTF method computes the metrics defined in Far Field by using the Near Field to Far Field transformation.

The NFTF measurement setup of UE RF characteristics for FR2 is capable of centre and off centre of beam measurements and an example setup is shown in Figure B.2.5.1-1:

Figure B.2.5.1-1: Example of NFTF measurement setup

The key aspects of the Near Field test range are:

– Radiated Near Field UE beam pattern is measured and based on the NFTF mathematical transform, the final metric such as EIRP is the same as the metric for the baseline setup

– A positioning system such as the angle between the dual-polarized measurement/link antenna and the DUT has at least two axes of freedom and maintains a polarization reference

– For setups intended for measurements of UE RF characteristics in non-standalone (NSA) mode with 1UL configuration, an LTE link antenna is used to provide the LTE link to the DUT. The LTE link antenna provides a stable LTE signal without precise path loss or polarization control.

– For setups intended for measurements in NR CA mode with FR1 and FR2 inter-band NR CA, test setup provides NR FR1 link to the DUT. The NR FR1 link has a stable and noise-free signal without precise path loss or polarization control.

The applicability criteria of the NFTF setup are:

– The DUT radiating aperture is D ≤ 5 cm

– Either a single radiating aperture, multiple non-coherent apertures or multiple coherent apertures DUTs can be tested

– If multiple antenna panels that are phase coherent are defined as a single array, the criterion on DUT radiating aperture applies to this single array

– D is based on the MU assessment in Annex B.1.4.3 of TR 38.810 [24]

– If the uncertainties can be further optimized, the MU may be reduced or D may be increased

– A manufacturer declaration on the following elements is needed unless the entire DUT size is contained in a sphere of diameter of ≤ 5 cm:

– Manufacturer declares antenna array size

– EIRP, TRP, and spurious emissions metrics can be tested.

B.2.5.2 Quiet zone dimension

Same as Annex B.2.2.2.

B.2.5.3 Quality of the quiet zone

Same as Annex B.2.2.3.

B.2.5.4 Measurement Distance

The NFTF system does not require a measurement distance of as in a standard far field range due to the use of the Near Field to Far Field transformation.

The measurement distance for any NFTF system implementation shall ensure that the DUT is not measured in the reactive near-field region and is adequate to meet the quiet zone dimensions defined in B.2.5.2.