EMC exhibits and demonstrations kick off Symposium in the Motor City

IEEE International Symposium on Electromagnetic Compatibility, Detroit, MI, August 18-22

Martin Rowe, Senior Technical Editor -- Test & Measurement World, 8/20/2008 8:23:00 AM

DETROIT, MI—Tuesday featured morning and afternoon technical demonstration sessions. The morning session included the ever-popular EMC consultant Doug Smith, who demonstrated how to use two current probes with a spectrum analyzer to find resonance in a cable. One probe connects to the spectrum analyzer’s tracking generator, which acts as a transformer injecting a voltage into an unterminated cable. The other current probe connects to the spectrum analyzer’s receiver and detects the resulting current in the cable. Smith conducted the measurements from 0-300 MHz with a 300-kHz resolution bandwidth. Smith also showed how using ferrite cores around the cable reduces the amplitude of the current.

The afternoon demonstrations included a set of three experiments by Professor Keith Hoover from Rose-Hulman Institute of Technology. Hoover uses the experiments to teach EMC to college juniors majoring in computer engineering. One experiment involves adding a common-mode choke to a DC-DC converter. The choke removes noise and ringing from the output. Students also change an RC time constant in the converter’s oscillator, which demonstrates how oscillator frequency affects converter efficiency.

In another experiment, students must design their own inductor with wire and add it to a wireless FM microphone transmitter built from discrete components. The inductance in the wire sets the transmitter’s carrier frequency. The experiment also demonstrates the affects that wire length has on circuit performance. It also highlights the need to keep all wires as short as possible, especially when the circuit is built on a prototyping board.

Several new products appeared on the exhibition hall this year. Teseq exhibited several new products including the AES 5500, an automotive transient emissions test system. Other introductions included an upgrade to the NSG 4070 EMC immunity test system that adds bulk-current injection. Also shown was the NSG 3040 test system that performs electrical-fast transient, surge, and power-quality tests.

Rohde & Schwarz introduced the ESL precompliance EMI test receiver. Two models range from 9 kHz to 3 GHz or 9 kHz to 6 GHz. It’s designed for early precompliance measurements of radiated emissions and is available with or without a tracking generator. The Model FSV signal analyzer lets you analyze signals used in GSM, EDGE, WiMAX, and other wireless networks. Its range covers 9 kHz to 7 GHz.

ETS-Lindgren has added several EMI antennas to its portfolio. The Model 3142D BiConiLog covers 26 MHz to 6 GHz and is designed for emissions testing to ANSI C63.4, FCC part 15 and part 18, and EN50022. You can also perform immunity testing to IEC 61000-4-3 with the antenna. The Model 3180 mini-biconical antenna lets you perform chamber characterization and spectrum monitoring at frequencies from 30 MHz to 1 GHz. The Model 3182 biconical antenna covers all VHF and part of the UHF broadcast bands with an omnidirectional pattern. The Model 3181 mini-biconical antenna covers 500 MHz to 18 GHz with a radiation pattern that conforms to CISPR-16 specifications.

A newcomer to the EMC test field, Amber Precision Instruments, exhibited an EMI immunity scanner system. The system consists of a mechanical arm that scans a radiating probe over a PCB assembly. The probe produces pulsed emissions that couple into the PCB where a receiving probe detects fields from the induced currents in the EUT.