Spherical Arch Scanners


MI-6850-ArchMI-6850 Family of Spherical Arch Scanners

MI Technologies is pleased to offer the MI-6850 Family of Spherical Arch Scanners for spherical near-field antenna measurements.

This accurate scanner supports spherical near-field testing with a scan radius from 1.2 to 10 meters.

The MI-6850, combined with the speed and flexibility of the MI-350 Advanced Microwave Measurement System (AMMS) and TICRA SNIFTD (Spherical Near-Field to Far-Field Transformation) software, provides a measurement system capable of handling a wide range of antennas from .1 - 140 GHz.

downloadpdfWhen integrated with an azimuth positioning control system, the MI-6850 delivers spherical near-field testing of antennas on an unprecedented scale of accuracy and efficiency.

Spherical scanning is accomplished by rotating the Antenna Under Test (AUT) on an azimuth positioning system while elevation scans are accomplished using a near-field probe mounted on the arch carriage. Phase and amplitude data is collected as the AUT rotates.

When using the MI-350 AMMS, multiple polarizations, channels and frequencies can be collected as the AUT rotates.

  • Ideal for spherical near-field antenna measurements
  • Up to 10 Meter scan radius
  • ± .005° angular position accuracy
  • .002" RMS radial accuracy
  • 90, 115, 135 and 180° versions

 

 

Specifications

  MI-6850-1.2 MI-6850-3 MI-6850-5 MI-6850-7 MI-6850-10
Nominal Scan Radius (to Probe Mounting Surface) 1.2 m 3 m 5 m 7 m 10 m
Elevation Travel Options1

90º
135º
180º

90º
135º
180º

90º
135º
180º

90º
135º
180º

90º
115º

Elevation Position Accuracy (Deg RMS)

0.002 (90º)
0.003 (135º)
0.005 (180º)

0.002 (90º)
0.003 (135º)
0.005 (180º)

0.002 (90º)
0.003 (135º)
0.005 (180º)

0.002 (90º)
0.003 (135º)
0.005 (180º)

0.002 (90º)
0.003 (115º)

Planarity of Scan Circle2
(Inches RMS)

0.003 (90º Travel)
0.003 (135º Travel)
0.003 (180º Travel)

0.005 (90º Travel)
0.006 (135º Travel)
0.007 (180º Travel)

0.005 (90º Travel)
0.006 (135º Travel)
0.007 (180º Travel)

0.005 (90º Travel)
0.006 (135º Travel)
0.007 (180º Travel)

0.005 (90º Travel)
0.007 (115º Travel)

Elevation, Maximum Speed (Deg/Sec) 1.2 1.2 1.2 1.2 1.2

Radial Axis Travel2
(Inches)

4 4 4 4 4

Radial Position Accuracy2
(Inch RMS)

0.002 0.002 0.002 0.002 0.002
Radial Axis, Maximum Speed (Inch/Sec) 1 1 1 1 1
Roll Axis, Maximum Load Capacity (lbs) 65 65 65 65 65
Roll Axis, Travel Options Continuous, ± 120º Continuous, ± 120º Continuous, ± 120º Continuous, ± 120º Continuous, ± 120º

Roll Axis, Position Accuracy2
(Deg RMS)

0.02 0.02 0.02 0.02 0.02
Roll Axis, Maximum Speed (Deg/Sec) 12 12 12 12 12
Maximum Load Capacity (lbs) 65 65 65 65 65
Overall Dimensions (L x W x H) 7’ x 19’ x 16’ (180º) 8’ x 16’ x 29’ (135º) 8’ x 26’ x 39’ (135º) 9’ x 31’ x 53’ (135º) 59’ x 45’ x 57’ (115º)
Net Weight (lbs) 10,000 15,000 21,000 35,000

55,000

Operating Environment Indoors Indoors Indoors Indoors Indoors
Temperature, Measuring (°C) 20, ± 2 20, ± 2 20, ± 2 20, ± 2 20, ± 2
Temperature, Operating (°C) 10 to 40 10 to 40 10 to 40 10 to 40 10 to 40
Humidity, Survival (% Relative Non-Condensing) 20 to 90 20 to 90 20 to 90 20 to 90 20 to 90

1 Custom Travel Available
2 Achievable

NOTES:

  • Position errors, planarity and repeatability apply when operated over a temperature range of +/- 2.8 degrees C about a fixed ambient temperature within the range of 18 degrees to 29.5 degrees C.
  • Better accuracy can be achieved using the error mapping functionality of the MI-710C position controller.

Mechanical Structure

1.2 Meter Design

  • The Theta axis uses precision ground curvilinear rails mounted to a ground structural ring that is aligned during installation. The curved, rack and pinion, torque-biased drive system achieves precision accuracy with zero backlash.
  • Probe interface uses kinematic mounts to achieve alignment repeatability and stability

3 - 10 Meter Design

Based on a truss system that provides several key advantages:

  • Extremely strong and stiff, yet simple structure provides inherent accuracy and repeatability of the probe's position
  • Arch system part count is minimized to reduce installation mechanical alignment time on site
  • Hardened steel track plates ensure long life
  • Precision machined steel cam follower track system

Enhanced Accuracy Option

MI's arch scanners can be configured with MI's Motion Control and Laser Technology to achieve even higher levels of measurement accuracy. This option can be used to characterize and compensate for errors that are repeatable. The compensation is determined as a combination of an off-line calibration procedure prior to measurement and several real-time updates to that calibration during the measurement. The motion of the near-field probe is compensated in real time to follow the calibrated path that will minimize position errors.

At the system level, position errors on one axis can be influenced by the position of other axes. To solve this problem, the MI-710C features coordinated motion with multi-axis error correction. Using a tracking laser, position error for an axis is measured as other axes are varied. A multidimensional error correction table is generated. The system is capable of including up to 4 inputs (e.g. position of other axes, temperature, etc.) in the correction algorithm.

Acquisition of error correction data using a tracking laser is now highly automated and therefore more economical to implement. For example, approximately 1,000 correction data points per hour can be measured. As a result, the entire arch system can be characterized in a matter of hours rather than days. This is particularly beneficial when characterizing/correcting system errors during final installation and periodic calibration.