Nearfield Systems Inc.
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About
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NSI near-field measurement systems are used world-wide for a variety of antenna measurement applications including the testing of antennas used in satellites, PCS/Wireless, radar systems and many other antenna applications. NSI systems are also used at leading universities and research institutions. The antennas used on these satellites are quite complex, supporting numerous beams, polarizations and frequencies. The following systems describe satellite test applications that NSI near-field measurement systems are used to support. JPL 8' x 8' NF Measurement System NSI designed and delivered an 8' x 8' scanner to JPL for use in qualifying the JPL Microwave Limb Sounder (MLS) satellite antenna. The scanner provides a highly accurate plane (3 microns rms) for measuring the performance of the MLS antennna. The scanner uses a high precision electronic tiltmeter measurements and a active heat control system to achieve its performance. The Microwave Limb Sounder (MLS) experiments measure naturally-occurring microwave thermal emission from the limb of Earth's atmosphere to remotely sense vertical profiles of selected atmospheric gases, temperature and pressure. TRW 40'x30' Horizontal NF Scanner NSI delivered a 40' x 30' horizontal NF Scanner to TRW for use in testing the payload antennas for the 4 Astrolink satellites. The system operates up to 50 GHz and can scan in planar, plane-polar, and tilted plane-polar modes to measure any of the apertures on the Astrolink satellite. Globalstar Satellite:NSI near-field measurement systems were used for flight qualification of the antennas used on board the first Globalstar Satellites. The Globalstar satellites are used to provide world wide communications from small handheld terminals. Three large near-field measurement systems built by NSI are located at Space Systems Loral in Palo Alto California, Alcatel Espace in France and Alenia Spazio in Italy. SWAS Satellite:NSI has designed and built three submillimeter wave near-field measurement systems operating at frequencies as high as 550 GHz. These scanners use granite structures with air bearings to obtain a Z positioning accuracy of a few wavelengths of light. One application of this system is the flight qualification testing of the NASA Submillimeter Wave Astronomy Satellite (SWAS), part of the SMall EXplorer satellite program. The SWAS satellite is intended to be launched by a Pegasus XL rocket later this year. Antenna test systems for wireless and PCS applications have taken off with the popularity of cell phones, PDAs and wireless networks. Many of these broad-beam antennas require cylindrical or spherical near-field systems for full coverage. The following systems describe PCS/cellular applications that NSI near-field measurement systems are used to support. Galtronics Spherical NF Measurement SystemNSI has installed two state-of-the-art spherical nearfield measurement systems for Galtronics, a producer of cell-phone antennas. The system provides complete spherical measurements of the antenna with or without human body mockups. Since 1978, Galtronics has designed and manufactured high performance antennas for the wireless communications market,including wireless mobile telephone handsets, Bluetooth devices, wireless local area networks, portable two-way radios, wireless local loop systems, and wireless data devices. Kathrein Spherical NF Measurement System NSI recently installed a custom spherical near-field system at Kathrein in Rosenheim, Germany. The system is used by Kathrein to test a variety of antennas including base station antennas for mobile telephones. The system includes the spherical near-field scanner, an RF subsystem consisting of an HP 8530A, an NSI designed Intergrated Frequency Converter (IFC) and high-speed synthesizers allowing multiple frequency acquisition on-the-fly at rates up to 2,000 measurements per second. The RF system supports measurements from .75 GHz up to 4 GHz. The data acquisition and processing functions are controlled by NSI's flagship software product NSI 2000. Here is a photograph of the NSI system installed in the chamber at Kathrein, and also a viewable panoramic image taken inside the chamber. (panoramic image requires LivePicture plugin) The antennas used in radar systems are quite complex, supporting numerous beams, polarizations and frequencies and often have complex pulse and timing relationships. The following systems describe radar applications that NSI near-field measurement systems are used to support. Raytheon GBR NSI installed the 23' x 12' (8m x 4m) vertical planar scanner used for the Raytheon Ground Based Radar (GBR) program, missile defense and similar radar systems. The scanner has a granite base and includes one of NSI's first laser optical correction systems and a dual arm rotary joint system for RF probe phase reference cable. The system is used to test a variety of ground based radar systems. Tobyhanna 300V-18x18 Vertical Planar NF scanner NSI delivered an 18' x 18' vertical planar scanner to Raytheon for use at the Tobyhanna test station for testing the Firefinder radar antennas. Research Institutions:NSI systems are also used by various universities and research institutions: The Aerospace Corporation in Los Angeles uses one of our systems for antenna measurements. California State University at Northridge (CSUN) is using one of our systems for graduate studies in electromagnetic engineering. Georgia Technical Research Institute has studied near-field test methods since the early 1960 time frame. They are a world leader in this type of work and use one of our systems as part of their continuing research activities. University of California, Los Angeles (UCLA) has been developing innovative bipolar near-field scanning methods under the direction of Dr. Yahya Rahmat Samii. The bipolar technique holds promise for both low cost test systems and for compact space based test systems. |
