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Spherical Near-field mmWave Measurement System


The NSI-700S-360 is the latest NSI development to measure stationary mm-Wave on chip antennas and is well suited to applications above 10 GHz. The NSI-700S-360 uses a multi-axis high accuracy stepper motor based positioning system to move the probe on a spherical surface while the AUT remains stationary. The system is large enough to incorporate RF converter modules from OML and VDI as part of the probe carriage assembly and maintain a probe tip radius of roughly 20" (500 mm). The mm-Wave modules are exchanged to cover the relevant frequency bands, leaving the rack and cabling portion of the RF sub-system intact, making for a very modular and upgradable test system. All positioners contain integrated RF rotary joints to maximize cable phase stability during testing and the Phi-axis positioner also contains a slip-ring assembly.


The table below shows the maximum AUT sizes that can be tested in spherical near-field mode over the intended band of operation of the system. For cases where the probe to AUT distance (approx. 500 mm) is sufficient to allow for far-field testing, the software allows for far-field measurements to be conducted. Based on the commonly used 2D^2/lambda rule, the
maximum AUT size that can be tested in pure far-field mode is also shown the table below:

Frequency [GHz] Wavelength [mm] Largest AUT Dim [mm] for SNF Largest AUT DIM [mm] for FF
10 30.00 400 86
50 6.00 300 39
75 4.00 200 32
110 2.73 136 26
140 2.14 107 23
170 1.76 88 21
220 1.36 68 19
325 0.92 N/A 15
500 0.60 N/A 12

The system interfaces with a wide variety of RF equipment. The system software runs on a dedicated measurement workstation and provides automatic setup of scans based on measurement parameters. Measured data can be processed for far-field or holographic back projection yielding complete characterization of the antenna's performance. A single data set provides information on antenna gain, side lobe structure, beam pointing and cross polarization.

The system is delivered fully assembled and aligned to minimize on-site installation effort.

  • Scan Area 360° Phi and 360° Theta (Practical limits are set by the user)
  • External adjustable limit switches allow the user to set fail-safe limits to protect RF equipment or AUT fixturing
  • Polarization stage included
  • No AUT motion
  • 10 - 500 GHz FF frequency coverage
  • Far-field measurements capability
  • Spherical Near-field measurements capability
  • Holographic back projection capability
  • Panther Motion Controller with angular structural correction capability
  • High accuracy positioners

Construction Theta, phi, and pol rotation stages with steel interconnect structure
Drive System Precision Stepper Motors
Scan Area 360° Phi and 360° Theta
Scan Radius (Probe tip to center) 500 mm (with WR15 probe)
Resolution 0.02° Phi and Theta, 0.01°Pol
Position Repeatability 0.03°
Rotational Speed 10°/sec Phi, 10°/sec Theta, 10°/sec Pol
Measurement Workstation PC with Windows operating system, keyboard, 17" LCD monitor
System Controller NSI Panther Motion Controller
Probe OEWG/SGH with mm-Wave module
Rotary Joints Qty-2 - DC-26.5 GHz, (Phi, Theta)
Power 100-240 VAC switchable, 50/60 Hz, 500 watts






    Including arm movement
    - Length: 123 in (3.2 m)
    - Width: 96 in (2.4 m)
    - Height: 103 in (2.6 m)

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Please contact the NSI Sales department to order this product.

Nearfield Systems, Incorporated
19730 Magellan Drive, Torrance, CA 90502, USA, Tel: 310.525.7000, Fax: 310.525.7100
Email: sales@nearfield.com. Visit our website: www.nearfield.com