Electromagnetic compatibility testing is an essential part of any electronic product development effort. Formal certification can take place in a laboratory dedicated to the task, but product developers themselves can speed the approval process.
As Dennis Handlon of Agilent Technologies put it in a recent article, “Because a final product must be evaluated, testing usually is performed at the end of the development process. If the product fails, time is lost while the designers find and fix the problems and then restart the process of compliance testing. Many companies have improved their chances of succeeding on the very first try by adding precompliance testing to their development process.”1
Handlon cautions that although precompliance measurements are not conclusive, “positive results are a good indicator that a new product is likely to pass full compliance testing.”
A lab able to provide full compliance testing will have equipment dedicated to the task, with instruments conforming to the requirements of the Comité International Spécial des Perturbations Radioélectriques’ CISPR 16-1-1 standard. But as Handlon writes, recent revisions of the standard support the use of more general-purpose instruments for some tests. In reference 1, he describes the use of a signal analyzer with an EMC measurement application to provide precompliance testing.
Rohde & Schwarz also supports the use of a general-purpose instrument for EMC test. Volker Janssen, senior product manager for EMI and signal analysis products at Rohde & Schwarz, explained that the company offers an existing EMI test receiver line for both full compliance and precompliance measurements but in 2011 focused on supporting spectrum analyzer users. For EMC applications, these users employ their spectrum analyzers with basic EMI functions such as quasi-peak (QP) detector and -6-dB bandwidth settings for commercial and MIL-STD testing mainly for precompliance testing, with the expectation the spectrum analyzer tests will be sufficiently reproducible to get the required certification from an accredited test house or official body in one shot.
Figure 1. Screen Shot of the FSV-K54 EMI Measurement Application
Courtesy of Rohde & Schwarz
According to Janssen, “The focus of R&S was to help these customers out and make life easier with an extended option called R&S FSV-K54,” a measurement application that works with the nine models in the R&S FSVR and R&S FSV spectrum analyzer families (Figure 1). The application, he said, makes it unnecessary for customers to invest in a test receiver solution when they can make use of an already purchased spectrum analyzer that provides the necessary functions and detectors to perform complete tests in accordance with commercial and military requirements up to 40 GHz.
The R&S FSV-K54 option contains standard-compliant EMI detectors such as QP, CISPR-average, and rms-average, and it supports EMC bandwidths for both commercial and military standards. It also offers limit line and transducer options for typical measurement tasks as well as a logarithmic frequency axis for displaying the measured spectrum. The ability to link the analyzer’s markers to the various EMI detectors helps users quickly find critical areas. R&S EMC32 and R&S ES-SCAN PC software packages support remote-controlled measurements and can be used to generate test reports and document measurement results.
Janssen said the company was prompted to develop the FSV-K54 application with the publication of new standards, such as CISPR 16-1-1 (ed. 3) 2010. It defines acceptable measurement results taken with a spectrum analyzer as long as the spectrum analyzer fulfills pulse-test requirements down to the standard’s 20-Hz criterion with the required dynamic range. Added Janssen, “The motivation is, of course, to use the existing test equipment more efficiently with a low additional investment of an EMI measurement application option.”
Rohde & Schwarz offers test equipment for emission testing and susceptibility tests (both precompliance and full compliance) for applications such as household appliances, IT systems, and medical equipment. Janssen noted the company also supports large facilities for aircraft immunity testing, adding that Rohde & Schwarz participated in the world’s largest such facility, the Boeing Electromagnetic Test Center for the Korea Agency for Defense Development in South Korea. Rohde & Schwarz worked in conjunction with ETS-Lindgren and other companies on the project.2
Janssen said time-to-market is very important for product success, and the corresponding development process, including EMC testing, should not be delayed. “Real-time measurements supported by FFT calculations implemented in FPGAs help to improve testing speed enormously in precompliance testing phases,” he said, adding that the CISPR/A standardization group accepts certain FFT measurements for full compliance testing as well.
“The concept allows baseband conversion and FFT measurements on the IF stages of test receivers and spectrum analyzers,” Janssen added. “The realization of a reproducible speed advantage without losing accuracy is the challenge for the manufacturers. The best and experienced manufacturers will win and serve this market requirement.”
Power Meters and Systems
René Dijkstra, general manager of DARE!! Instruments, said two recently introduced products are the RadiPower Pulse Power Meter and the RadiCentre 7.2 Modular Test System. The RadiPower, he said, is a very fast power meter that operates at 1 MS/s (Figure 2). As such, it can perform extremely fast EMC tests and capture radar pulses and, explained Dijkstra, is the only power meter compliant with ETSI EN 300 328.
Figure 2. RadiPower Pulse Power Meter
Courtesy of DARE!! Instruments
Dijkstra described the RadiCentre 7.2 as a flexible and modular EMC test system (Figure 3). “The front has one button less than an iPhone—namely, none,” he said. In standby, it complies with the new Eco standards and consumes less than 0.75 W. The system is switched via the touchscreen. On the 7.2 version, the power supply and the CPU now are plug-in cards, allowing easy maintenance and upgrade while leaving seven of the instrument’s nine slots free for instruments and controllers like power meters, signal generators, field probes, antenna and mast controllers, switches, and I/O controllers.
Figure 3. RadiCentre 7.2 Modular Test System Front (top) and Back (bottom)
Courtesy of DARE!! Instruments
“As a result, one 19” inch system is all it takes to create a complete EMC test center,” Dijkstra said. The unit can communicate through GPIB, LAN, or USB. Its specially designed grips allow easy handling of the system, and it can still be mounted in a 19-inch rack without modification. In addition, the lack of internal wiring makes the system extremely robust.
Dijkstra said DARE!! Instruments is a relatively small player that can only survive in the competitive EMC instrument market through innovation. He said that DARE!! owns its own accredited EMC test laboratory, “so we know what is important and yet missing in the EMC test market.” The company also offers RadiMation EMC Test Software, which supports all brands of EMC test equipment and standards and even proprietary tests ranging from standard CE and FCC to military and automotive to aerospace.
Compliance Software
Gregory Senko, president of Teseq, said his company recently introduced a major release of its Compliance 5 RF lab software. The new release includes all the capabilities and flexibility of the previous Compliance 3, he said, but adds market-specific application packages with simple, yet comprehensive, menus and examples of equipment configurations that make the software faster and easier to implement. Basic Compliance 5 versions incorporate an application package for commercial test standards.
Senko said the market-specific application packages with their menu-driven user interfaces were created to provide a comprehensive solution for specific testing needs. The commercial application includes a fully automated process for optimization of radiated emissions measurements. He added, “Although the previous Compliance 3 versions of the software allowed tremendous flexibility, the setup and customization involved more work than most customers were willing to invest.”
The new Compliance 5 software has an application package that serves most commercial and industrial product testing, Senko said. Application packages also are available for MIL 461 military, DO-160 aerospace, and reverb chamber testing, and a package for automotive testing will be introduced soon.
“The rising cost of support and managing multiple users with varied capabilities are two issues becoming more important to our customers,” Senko added. “Teseq offers affordable support contracts for individual licenses as well as site licenses, which reduce the cost of ownership per installed software seat.”
Also, he said, the application packages have helped decrease support requirements. The software has a user administration feature that allows a system administrator to assign individual workspaces and authorizations as well as access to company published setups and procedures.
Probes and Analyzers
EMC Test Design LLC recently introduced the PI-03P Probe and SFA-S Selective Field Analyzer. The PI-03P Broadband Isotropic Electric Field Probe measures the RF field produced by microwave radars. It offers a fast sampling capability and can measure RF bursts as short as 1 µs. It operates over the 100-MHz to 18-GHz frequency range, and the field-strength range is 70 to 1,400 V/m. It serves in military and automotive applications. A company spokesperson said the probe addresses the proliferation of impulse and high crest factor RF signals in radars and high-power communications links using various pulse-modulation schemes.
The SFA-S is an active broadband isotropic antenna combined with a portable USB-powered spectrum analyzer (manufactured by a third party to EMC Test Design’s specifications). The OFA-S Antenna has a frequency response independent of antenna or electric field orientation. It can display the field strength and frequencies of the signals on the screen of any PC and be used for RF safety, regulatory, and spectrum monitoring applications.
The spokesperson said that customers not wishing to purchase the SFA-S can use the company’s OFA-S Omnifield Antenna with any spectrum analyzer. However, such a combination, he stressed, will be more expensive and require that the operator account for antenna factors—a task that is automated with the SFA-S.
Amplifiers and Receivers
AR RF/Microwave Instrumentation is revising its A225 amplifier family, making models smaller yet more powerful with wider frequency ranges. A225 models now are available with power up to 16,000 W and cover 10 kHz to 225 MHz.
Model 600A225, one of the newest family members, is a 600-W RF power amplifier for the 10-kHz to 225-MHz frequency range (Figure 4). It is equipped with a digital control panel that provides both local and remote control using IEEE 488, RS-232, USB, and Ethernet interfaces. The digital control panel uses a 3.75” diagonal graphic display, menu-assigned soft keys, a single rotary knob, and four dedicated switches to offer extensive control and status-reporting capabilities. The 600A225 offers readily available RF power for typical applications such as RF susceptibility testing, antenna and component testing, watt-meter calibration, particle accelerators, plasma generation, and communications and can be used as a driver for higher power amplifiers.
Figure 4. 600A225 600-W RF Power Amplifier
Courtesy of AR RF/Microwave Instrumentation
Last year, Agilent Technologies introduced its N9038A MXE EMI Receiver (Figure 5), which is compliant with CISPR 16-1-1 2010 and MIL-STD-461F. Mark Terrien, EMC business manager for Agilent, said the instrument provides the measurement accuracy and sensitivity necessary for EMC testing while delivering diagnostic spectrum analysis capability to help identify and troubleshoot sources of interference.
Figure 5. N9038A MXE EMI Receiver
Courtesy of Agilent Technologies
Terrien said that with the MXE, Agilent now offers a high-quality receiver that meets the needs of EMC professionals as they wrestle with issues of throughput and accuracy. Time-to-market is a key driver for both commercial and military customers, he said, adding, “EMC professionals involved with both compliance verification and precompliance analysis/diagnosis play a key role in product delivery and can provide a significant competitive advantage when they improve the throughput of their facilities. High throughput not only gets the product to market efficiently, but also keeps operational costs low.”
Agilent has incorporated a range of tools into the new receiver to help facilitate measurement throughput, said Terrien, including fast-scanning capability for suspect list collection, built-in testing to both limits and margins, and customer-configurable system setup. In addition, spectrogram, zero span, and Agilent-exclusive strip-chart capabilities help facilitate troubleshooting and diagnostics. The MXE features an all-digital IF stage to enhance measurement accuracy by removing errors typically introduced by analog circuit elements in the IF signal chain.
Terrien added that Agilent also offers an EMI measurement application that runs on the company’s X-Series Signal Analyzers, so customers can perform precompliance testing, as his colleague Handlon explained in reference 1. “This is a cost-effective way to resolve potential EMI issues early in the design process to avoid costly rework or delays to market,” he concluded.
The consensus is that time-to-market is critical and that success in prompt EMC approval begins with an effective precompliance test strategy that can help attain first-pass success in full compliance test. Whether you are looking for dedicated EMC test equipment or for a way to use equipment you already have for EMC precompliance test, vendors are striving to meet your needs.
References
1. Handlon, D., “Achieving Full Compliance on the First Try,” EE-Evaluation Engineering, October 2011, p. 32.
2. “Electromagnetic Test Center at the Korea Agency for Defense Development,” ETS-Lindgren White Paper, 2008.
For More Information