In the December 20, 2011 Issue:

New Spherical Near-field Supports Measurements to 500 GHz. NSI recently introduced the NSI-700S-85 Theta/Phi Spherical Near-field Scanner...

PNA-X Wideband Pulse Mode Driver. NSI now supports wideband pulse mode operation for the Agilent N522x PNA and N524x PNA-X models...

FF-MARS Available for Improved Far-field Measurements. For the past seven years, NSI's Mathematical Absorber Reflection Suppression technique...

Featured NSI Script: Google Earth Contour Overlay. This newsletter's featured script allows the display of antenna contour plots with topographical data...

NSI Exhibits at AMTA 2011. Autumn in Denver Colorado provided a spectacular setting for this year's AMTA Symposium, and NSI was on hand to demonstrate....

Upcoming NSI Events. NSI will be participating in the following upcoming events...

Learn More About Near-field Antenna Measurements. If you've wondered about near-field measurements and whether they can improve your antenna test...

New Spherical Near-field Supports Measurements to 500 GHz

NSI recently introduced the NSI-700S-85 Theta/Phi Spherical Near-field Scanner with precision positioners. The system is designed to test antennas from 10 – 500 GHz and uses a dual-axis high accuracy stepper motor-based positioning system with encoders, allowing for position triggering of the receiver to within 0.005 degrees. The scanner is designed to accommodate mm-Wave up and down converter modules to ensure maximum RF system stability. The mm-Wave modules are designed to cover the standard frequency bands from 50 GHz and up, without repositioning the primary RF sub-system, making for a very modular and upgradable test system. Both positioners contain integrated RF rotary joints and slip ring assemblies to maximize cable phase stability during testing. The Phi stage (lower) load capacity allows for the integration of microwave probes in order to test antennas on chip, as one possibility.

New 700S-85 Theta/Phi Spherical Near-field Scanner at AMTA 2011

The system may be configured with the NSI Panther 9000 or Agilent PNA-X based RF sub-system, near-field probes and standard gain horns. A measurement workstation, scanner control system and NSI2000 Software is included with each system. The NSI2000 Software provides automatic setup of scans based on measurement and antenna 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 may be configured as a turn-key test system to minimize compatibility and configuration issues.

PNA-X Wideband Pulse Mode Driver

NSI now supports wideband pulse mode operation for the Agilent N522x PNA and N524x PNA-X, and recently demonstrated this capability at the AMTA Symposium held in Englewood, CO. The NSI solution does not require PNA options 008 or 025, which are required for RF narrowband pulsed measurements.  In wideband pulse mode, the receiver trigger is synchronized to the RF pulse and only requires a single pulse to complete the measurement. The NSI solution uses the NSI-RF-5501 Pulse Generator/Synchronizer to generate and synchronize the RF pulse. Alternatively, an external pulse generator may also be used.  Either PNA option 021 or an external PIN switch may be used to modulate the RF signal. At 5 MHz IFBW, the minimum pulse width that can be measured is 200 ns. Advantages of wideband pulse mode are that the performance is independent of the pulse duty cycle, and it can work on a standard PNA or PNA-X without pulse options.  Please contact sales@nearfield.com to learn more about this capability and other NSI’s solutions for the Agilent PNA and PNA-X. 

Far-Field MARS Available for Improved Measurement Performance

For the past seven years, NSI’s Mathematical Absorber Reflection Suppression technique, better known as MARS, has been used with enormous success in quantifying and subsequently suppressing range multi-path effects, first with spherical, then cylindrical and lastly with planar near-field antenna measurement systems. Very recently, NSI has made a breakthrough that for the first time, allows the MARS measurement and post-processing technique to be successfully deployed to correct antenna pattern data taken using direct far-field or compact antenna test ranges (CATRs) where only a single great circle pattern cut is acquired. This new technique can work on a single frequency measurement and does not require the use of additional hardware or auxiliary measurements. The plot below shows an x-band corrugated horn that was measured with, and again without a 0.6 x 0.6 m flat reflecting metal plate. It is clear that MARS processing has completely removed the effects of the scattered fields (red trace) from the measurement and is a very dramatic demonstration of the effectiveness of this revolutionary technique.

Comparison of X-band Horn Pattern With and Without Metal Plate
(Approx. 20 dB improvement in Range Multi-path Effects)

For more additional information about MARS and other NSI software improvement techniques, visit our website or browse our online technical paper archive.

Featured NSI Script: Google Earth Overlay

This newsletter’s featured script provides the capability to analyze antenna response with respect to topographical data. The script takes a contour plot in terms of amplitude versus amplitude/elevation and converts it to a file that is overlaid on Google Earth. This conversion allows setting the position and orientation of the antenna by entering the satellites latitude, longitude and altitude, and by setting the point on earth where the antenna's boresight is pointed together with the rotation around its boresight axis. The antenna pattern is then mapped on the earth, taking into account position, orientation and the spherical earth.

The process to create the overlay takes three simple steps:

1. Generate a contour plot in Azimuth/Elevation that is to be projected onto the earth
2. Run the script, which allows entry of location and pointing of the antenna. This will automatically open Google Earth and overlay the plot
3. Analyze and print for Google Earth

The example below shows the original far field antenna pattern (a shaped beam) as a contour plot, the script graphical user interface (positioning the beam over Chile), and the resulting overlay on Google Earth.

NSI2000 Contour Antenna Plot Overlay with Google Earth

To obtain this script or learn more about NSI scripting capability, please contact your local NSI-representative or pbetjes@nearfield.com.

NSI Exhibits at AMTA 2011

Autumn in Denver Colorado provided a spectacular setting for this year’s AMTA Symposium, and NSI was on hand once again to demonstrate the latest advances in antenna measurement technology.  This year’s symposium drew over 400 registered attendees and 37 exhibitors.  NSI once again hosted the Sunday Night Reception where participants and their guests joined us in the Spotted Dog Pub for appetizers, cocktails and the opportunity to unwind and catch up with old companions.

The NSI exhibit booth showcased a total of six displays, with three scanners providing live measurement demonstrations of our planar, cylindrical and spherical near-field measurement capability.  Two of these systems were equipped with NSI Panther 9000 RF sub-systems, while another demonstrated the Agilent 50 GHz PNA and its advances of Mathematical Absorber Reflection Suppression (MARS) for planar near-field measurements. Of special interest was the new NSI-700S-85 mm-Wave Spherical Near-field Scanner with precision positioners, which is designed for testing from 50 – 110 GHz, and higher with optional mm-Wave modules, and is ideal for measuring antennas up to 20 inches (500 mm) in diameter. NSI also presented five technical papers at the symposium, two of which were on MARS improvements for planar and far-field measurements.

AMTA 2011 Demonstration of Planar/Cylindrical/Spherical Near-field System

NSI's John Demas Explaining Near-field Measurements to Future Antenna Engineers during AMTA 2011 Student Day

Upcoming NSI Events

February 14 - 17

March 26 - 30

May 2012

June 17 - 22

NSI Short Course (Torrance, CA)

EuCAP 2012 (Prague, Czech Republic)

UCLA Short Course (Northridge, CA)

IEEE MTT-S IMS 2012 (Montreal, Canada)

See NSI at other tradeshows and short courses during 2012.

Learn More About Near-field Antenna Measurements

If you've wondered about near-field measurements and whether they can improve your antenna test process, see NSI's Near-field 101 page for a short tutorial on near-field measurements or view our on-line videos at http://www.nearfield.com/AMTV/index.htm.