Antenna Element position in 3GPP-38.901

Hi

In Chapter 7.3 of 38.901. it says:

"Antenna numbering on the panel illustrated in Figure 7.3-1 assumes observation of the antenna array from the front (with x-axis pointing towards broad-side and increasing y-coordinate for increasing column number)."

But in 5G Toolbox, when calculating position of each antenna element by calling function makeAntennaArray.m, it seems didn't align with 38.901.

"sfn = @(dH,dV,dgH,dgV)[ [dV; 0; 0] [0; dH; 0] [0; 0; 0] [dgV; 0; 0] [0; dgH; 0] ];"

per my understanding, it should be

"sfn = @(dH,dV,dgH,dgV)[ [0; 0; dV] [0; dH; 0] [0; 0; 0] [0; 0; dgV] [0; dgH; 0] ];"

Thanks for your support.

[Maab]

I want know all Thing about 3GPP antennaa and I Can get any information

[Dyuman Joshi]

@Maab - How is that related to MATLAB?

Answer 1

[Iain Stirling]

Hello Hu,

Our understanding is that the comment "x-axis pointing towards broad-side and increasing y-coordinate for increasing column number" only applies to Section 7.3, to explain how the antenna numbering relates to Figure 7.3-1. More specifically, we think the comment "x-axis pointing towards broad-side" applies to that section but not to the model in general. Our understanding is that in the co-ordinate system defined in Section 7.1.1, the broad-side of the array points along the z-axis. This means the array is lying on the x-y plane, with the broad-side pointing to the zenith (+ve z-axis). This is why the downtilt angles used in the model are always > 90 degrees, as a 90 degree downtilt is required to make the array "stand up". See for example Table 7.8-1 which has downtilt angles of 102 and 110 degrees.

Regards,

Iain.

[Hu Yuping]

Hi, Iain

Thanks for your reply, your comments make sense.

BTW, if so, will it better to set Orientation in TransmitAntennaArray (the property of nrCDLChannel) to [0, 90, 0] as default value?

the current default value is [0, 0, 0], and make the TX antenna (usually, it is BTS side, right?)not "stand up".

---- Update after try Orientation with 90 degrees ----

Hi, Iain

I set the downtilt to 90 degrees, but seems the orientation didn't impact the antenna element position.

In makeAntennaArray, the "antennaArrayStructure.Orientation" doesn't invovled when calucation AE postion.

And generateClusterGains\ getLocationTerm, it neither use origenation.

So IMHO, this will makes the beam always point to the Z-Axis. is this expexted?

Further, i have another finding. Consider below scenario.

Using Rx AE as isotropic, Tx AE as 38.901. Set AOD\ZOD to 0\90.

set downtilt to 90, the field pattern is much lower than value of set downtilt to 0.

if set downtilt to 90 make antenna stand up, then it should give max field patten in direction of X-Axis (AOD = 0, ZOD = 90). but the result seems give opposite conclusion.

it will be nice if you can clarify it. Much thanks.