SOUTHWEST RESEARCH INSTITUTE

Electromagnetic Compatibility Research Group

| Structural and Mechanical Engineering Department | Mechanical and Materials Engineering Division |

EMC Research Program Summary

Electromagnetic compatibility (EMC) is the ability of electronic and electrical equipment and systems to operate without adversely affecting other electrical or electronic equipment. Electromagnetic compatibility testing also measures how the equipment is affected by other sources of interference such as powerline transients, radio frequency (RF) signals, digital pulses, lightning or cosmic influences. SwRI EMC services include EMC testing, EMC design, and EMC analyses. Our extensive facilities, equipment and experienced staff provide a one-stop shop, assisting clients in numerous industries. Field services are also available.

Electromagnetic Compatibility Laboratory Equipment

EMC test facilities are comprised of a stirred-mode chamber, shielded enclosures, a radio frequency (RF) anechoic chamber, an open-area test site, a tri-plate-line (TPL) fixture and transverse electromagnetic (TEM) cells. These are described in more detail below:

Stirred-Mode Chamber

SwRI designed the stirred-mode chamber facility to accommodate testing an entire vehicle as well as smaller components and subsystems. The stirred-mode facility provides highly efficient immunity testing because the device being tested is immersed in a quasi-homogeneous electric field. This evaluation method minimizes test time and cost.

Shielded Enclosures

SwRI EMC facilities include eight shielded enclosures, ranging in size from 10 x 20 x 10 feet to 20 x 30 x 12 feet. All enclosures have filtered 120/208 three-phase 60 Hz power, with 50- and 400-Hz power available, and can be configured with RF absorptive material. Two sets of enclosures share a common wall and can be configured for performing shielding effectiveness measurements (IAW MIL-G-83258B). Each enclosure provides:

• 100 dB of attenuation to electric fields from 1 kHz to 25 MHz

• 100 dB of attenuation to plane waves 25 MHz and above

• 20 dB H-Field attenuation at 1 kHz increasing to 100 dB at 150 kHz

Radio Frequency Anechoic Chamber

SwRI has an anechoic chamber available for EMC tests and evaluations. It measures 28 x 16 x 16 feet and provides RF attenuation in excess of 100 dB, 30 MHz and above. This facility can be fully configured with anechoic material or used without the material on the floor to expose the ground plane.

Open-Area Test Site

SwRI maintains an open-area test site to measure radiated emissions from electronic and electrical equipment. The level test site is clear of electromagnetic reflecting surfaces for a minimum radius of 32 meters. Three-phase 60- and 400-Hz, single-phase 50-Hz and DC power sources are available to test systems. The open-area test site has a large, continuous metal ground plane (20 x 40 meters) and a 4-meter diameter flush-mounted turntable. Directly under the turntable, there is an air-conditioned vault for support equipment. The turntable is capable of supporting 15,000 pounds to conduct tests in accordance with:

• ANSI C63.4

• CISPR

• IEC

• ISO standards

Tri-Plate-Line Fixture

A TPL test fixture, designed and built by SwRI in accordance with SAE specification SAE J1113-25, is used to conduct radiated immunity evaluation of various automotive modules, sensors, and subsystems and their associated wire harnesses. The TPL is used to generate E-fields in excess of 400 volts per meter from 1 MHz to 200 MHz and 200 volts per meter from 200 MHz to 1 GHz.

Transverse Electromagnetic Cells

SwRI has three TEM cells ideal for EMC testing of small modules and brass board prototypes. The largest cell operates over the frequency range of DC to 220 MHz. SwRI built two additional cells to the Crawford cell design; one operates from DC to 500 MHz, and the other, from DC to 1 GHz.

For more information about EMC, contact Eric Dornes at (210) 522-3330 or Jenny Ferren at (210) 522-2329.
 

| Structural and Mechanical Engineering Department | Mechanical and Materials Engineering Division |

Southwest Research Institute^® (SwRI^®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions.

January 08, 2013