Original Date: 07/25/2005
Revision Date: 09/12/2006
Best Practice : Production Test Cell
The need to test large quantities of production antennas led Northrop Grumman Electronic Systems to adopt proven Commercial- Off-The-Shelf Near-Field Scanning Technology and its associated software and to use Test Cells instead of compact ranges. This has enabled Northrop Grumman Electronic Systems to realize a 50% reduction in the time required to test an antenna, enhanced measurement capabilities, and a 70% reduction in floor space requirements for the test facility.
In 1999, an imminent production run of 80 fourth-generation Electronically Steerable Antennas prompted Northrop Grumman Electronic Systems (NGES) to review existing “compact” antenna testing ranges to determine their ability to make the required measurements and maintain the production schedule. The review indicated that the existing ranges were not suitable for a number of reasons, including limited availability and testing capability. Rather than build another compact range, management decided to implement proven Commercial-Off-The-Shelf (COTS) Near- Field measurement technology in an antenna measurement “cell” where the antenna could be wheeled directly from the assembly floor. There the cart and antenna are aligned using special laser positioning sensors to correlate the X- Y scanner’s position to antenna-centered coordinates. The antenna cart rides into the test cell on ramped wheel guides fitted with end stops. Gravity holds the cart in place. Laser sensor and scanner X-Y motion are then used to “find” antenna reference points in scanner X-Y-Z coordinates. The acquisition of current state-of-the art Near-Field Scanning Technology hardware included a switch from 100% NG legacy software code, which was difficult to support, to 10% NG code and 90% proven COTS software code. All software is ISO 9001 approved.
As a result of this change in approach and equipment, the time to test the antennas has been reduced from 80 hours to 40 hours, and the switch from compact ranges to Test Cells has resulted in a 70% reduction in floor space required for the test facility. The new Test Cell has eliminated the need for a reflecting collimator and a separate positioner, resulting in substantial production costs. Enhanced measurement and analysis capabilities include the ability to acquire up to 2,000 partial hemispheres in a fraction of the former time and the ability to generate holographic back projections for spotting defective array elements. Future pre-planned product improvement plans include the development of a scanner that can be used to tune antennas in the field while they are mounted on aircraft.
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