F.5 Orthogonal cut grid

37.145-23GPPActive Antenna System (AAS) Base Station (BS) conformance testingPart 2: radiated conformance testingRelease 17TS

F.5.1 General

Here, at least two cuts (default) shall be used, an optional third cut can be used. The alignment of the cuts must be along the symmetry planes of the antenna array. No alignment is required for spurious emissions.

When alignment is required:

1. The first mandatory cut is a horizontal cut passing through the peak direction of the main beam.

2. The second mandatory is a vertical cut passing through the peak direction of the main beam. Using the data from these two mandatory cuts, a conditional pattern multiplication can be used.

3. The third optional cut is a vertical cut orthogonal to the first and the second cut.

When alignment is not required, the cuts can be aligned arbitrarily.

Once the number and the orientation of the cuts are decided, the total EIRP is measured on the orthogonal cuts and the TRP is then calculated as follows: First the contributions from each cut is calculated as:

where P is the number of sampling points in the cut. The final contribution for all cuts is calculated as:

where N is the number of cuts. Note that when orthogonal cuts are measured, the intersection points are measured multiple times and the repeated values can be removed from the samples before averaging.

When two cuts measurements are used, a conditional pattern multiplication can be applied. The following are the conditions for applying pattern multiplication:

i. The vertical cut (and the main beam) is in the -plane

ii. The frequency of the emission is within the downlink operating band.

iii. The bandwidth of the emission is the same as the bandwidth of the in-band modulated signal

iv. The emission appears/disappears when the Tx power is turned on/off.

v. The antenna arrays of the EUT

1. Have rectangular grids of antenna element positions

2. Have symmetry planes that are vertical and horizontal.

3. Have parallel antenna planes

The antenna array is here assumed to be placed in the yz-plane. The pattern multiplication is performed in uv-coordinates and the data in the two cuts are denoted at and a vertical cut with data at . The data is split in two parts corresponding to the forward and backward hemispheres. The uv-coordinates are the projections of the angular directions onto the antenna plane, here the yz-plane. Using the spherical coordinates as depicted in figure F.2.2.-1 the u and v coordinates are defined as:

Note that only the data on the cuts are measured.

Calculate power density/EIRP values outside the two cardinal cuts as

The pattern multiplication is applied separately for the forward (fwd) and backward (bwd) hemisphere. The TRP is then calculated as:

NOTE: The numerical singularity at must be treated with care, e.g. by change of variables.

F.5.2 Operating band unwanted emissions

The procedure is as follows:

1) Follow steps described in annex I.5.1 for the first two mandatory cuts and calculate the TRPEstimate.

2) Compare the TRPEstimate to the limit.

3) If the TRPEstimate is above the limit, perform the measurement on an additional third cut and repeat steps 1 to 2.

F.5.3 Spurious unwanted emissions

The procedure is as follows:

1) Follow steps described in annex F.5.1 for two cuts and calculate the preliminary TRPEstimate.

2) Add the appropriate correction factor ΔTRP according to table F.5.3-1 to ensure overestimation with 95% confidence.

3) Compare the corrected TRPEstimate (including ΔTRP) to the limit.

4) If the corrected TRPEstimate is above the limit, perform the measurement on an additional third cut and repeat steps 1 to 3.

Table F.5.3-1: The correction factor for two or three cuts dense sampling

Three cuts

Two cuts

Correction factor ΔTRP (dB)

2.0

2.5