Application Card | Version 01.00

IDENTIFYING DEFECTIVE SINGLE

ELEMENTS IN ANTENNA ARRAYS

Fault identification in single elements of antenna arrays by scanning in near-field range and applying the

near-field to far-field transformation method

Your task

Antenna arrays have been used extensively in different ap-

plications, including satellite and radar. One of the main

advantages of using antenna arrays is beamforming. It al-

lows flexibility and control over the antenna radiation pat-

tern, resulting in a more efficient and well-directed beam.

This is why massive MIMO antennas play an important

role in 5G infrastructures, including mobile backhaul,

point-to-point antennas as well as base stations. These

arrays make it possible to transmit an extremely high

amount of data with ultra-reliable low latency communica-

tions in 5G.

The complexity of designing and producing antenna ar-

rays should not be underestimated. In particular planar de-

signs such as microstrip patch antenna arrays are prone to

phase errors if RF substrate parameters vary over different

production units. Although it is possible to test the RF per-

formance and 3D antenna pattern of antenna arrays over

the air, what happens when the measured results differ

from expectations? Individual antenna elements may be

faulty, but detecting the error within a 64 × 64 antenna ar-

ray by trial and error is extremely time- and cost-intensive.

Hence, finding an alternative, more efficient solution can

save a huge amount of time and money.

Rohde & Schwarz solution

To resolve this issue, Rohde & Schwarz has developed the

ideal solution to efficiently identify individual defective el-

ements in magnitude and phase within an antenna array.

Implementing this solution requires an antenna chamber

and a high-quality vector network analyzer, for example

the R&S®ZVA equipped with the R&S®AMS32 OTA per-

formance measurement software. This setup makes it

possible to perform near-field to far-field transformations

based on the fast irregular antenna field transformation al-

gorithm (FIAFTA) used in R&S®AMS32.

The measurement procedure for finding defective ele-

ments within an antenna array starts with a field measure-

ment that covers at least the main beam region of the

antenna array. The probe antenna measures over the sam-

pling grid by moving in both azimuth and elevation with

the help of the 3D positioner. After the measurements,

the FIAFTA algorithm is employed during post-processing

so that the equivalent electrical surface currents and the

equivalent magnetic surface currents can be plotted on

an arbitrarily shaped object. The graphical representation

of both types of equivalent surface current makes it easy

to visualize and differentiate functional and defective ele-

ments within the antenna array.

Rohde & Schwarz GmbH & Co. KG

www.rohde-schwarz.com

Rohde & Schwarz training

www.training.rohde-schwarz.com

Rohde & Schwarz customer support

www.rohde-schwarz.com/support

R&S® is a registered trademark of Rohde & Schwarz GmbH & Co. KG

Trade names are trademarks of the owners

PD 3608.4239.92 | Version 01.00 | March 2020 (sk)

Identifying defective single elements in antenna arrays

Data without tolerance limits is not binding | Subject to change

3608.4239.92 01.00 PDP 1 en

3608423992

Antenna test chamber

Depending on the space and frequency requirements,

you can choose between the R&S®ATS1000 antenna

test chamber and the R&S®WPTC wireless performance

test chamber. The R&S®ATS1000 is mobile, compact and

has an operating frequency from 18GHz to 87GHz for

DUTs up to 40cm in diameter. On the other hand, the

R&S®WPTC is more flexible in terms of frequency range

and DUT size, covering 400MHz to 90GHz for DUTs up to

1.2m in diameter.

R&S®AMS32 and FIAFTA algorithm

R&S®AMS32 is the base measurement software developed

by Rohde & Schwarz to support all related OTA and an-

tenna measurements. The R&S®AMS32-K50 NF-FF trans-

formation option makes it possible to perform accurate

near-field to far-field transformations based on FIAFTA.

This algorithm was developed at the Technical University

of Munich and has been proven to be highly correlated to

far-field measurement results. To visualize the equivalent

currents of all shapes, both the R&S®AMS32-K52 and the

R&S®AMS32-K52U option are required. They make it easy

to identify defective elements in an antenna array.

Key features and benefits

►

Optimization of time to market by efciently identifying

errors in the R&D stage and in sample testing during

production

►

Analog and digital phase shifters validation

►

Uniformity verication of phase distributions

►

Repeatability check on multiple antenna arrays

►

Quick visual check

The R&S®ATS1000 includes a high-precision positioner in order to get the 3D data

2D equivalent current plots in magnitude and phase for an

antenna array

Antenna array Antenna array with synthetically

introduced defect by placing a

rectangular metal plate on the

antenna surface

Magnitude of equivalent magnetic

currents (|M

|) in the array plane

Magnitude of equivalent magnetic

currents (|M

|) in the array plane with

synthetically introduced defect

Phase of equivalent magnetic currents

(arg(M

)) in the array plane

Phase of equivalent magnetic currents

(arg(M

)) in the array plane with synthet-

ically introduced defect