EMC - Electromagnetic Compliance and ESD - Electrostatic Discharge

EMC is fundamentally about peaceful coexistence: An electrical device must function correctly in the presence of interfering signals and not unduly disturb the environment with its own emissions. Specific emissions and immunity limits are set in the various EN, ETS, ANSI, FCC, VCCI, and CISPR EMC standards.

Systems Engineering is the theme of the 2010 IEEE EMC Society’s International Symposium on Electromagnetic Compatibility (ISEMC) July 25-30 in Fort Lauderdale, FL. The five-day program at the Greater Fort Lauderdale/Broward County Convention Center will incorporate technical paper sessions, workshops, tutorials, the Global EMC University, demonstrations, experiments, special sessions, working group meetings, and exhibitors.

Part 2

EMC Test Amplifier

The 7224 Amplifier can be used when testing to a range of susceptibility standards including Ford EMC-CS-2009, DO-160, MIL-STD-461, and T1.315-2001. Depending on the configuration, the 7224 provides up to 1,500 W and has an operating bandwidth of DC to 200 kHz and a 70 V/µs slew rate. It produces up to 30 A of 13.5 VDC with 2-V pk-pk of line disturbances from DC to 150 kHz and up to 160 V peak and 50 A peak. The 7224 features a small chassis size for benchtop or rack-mounted operation.

AE Techron

Patriotic-Colored Wristbands

The 09200 4-mm Premium and 09201 Jewel® MagSnap are date-coded adjustable metal expansion wristbands featuring a red, white, and blue color combination. Both models have a medical-grade series stainless steel backplate and links, and the snap on each one provides a consistent 1- to 5-lb release per S1.1 requirements to prevent accidental disconnects while ensuring personnel will not be tied to the workstation. The 09201 also has a magnetic connection between the wristband and the coil cord.

Desco

Suspension Packaging

Suspension packaging and conductive cardboard shipping boxes recently joined the ALX selection of ESD-safe paper, printer rolls, tags, and file folders. The conductive/dissipative combined suspension packaging eliminates the need for void-fill or bubble-wrap materials, making it possible to ship products without ESD or physical damage. The permanently static-dissipative paper comes in single sheets in several sizes and colors and is compatible with clean-room class 10,000. Standard and custom tags for audits, repairs, rework, and work in progress are available in 12 colors with or without static-safe string.

ALX Technical

Continual-Use Seating

The Intensive Plus™ line of chairs, designed to provide reliability in continual-use, 24-h operation environments, is available in an ESD version with metal-to-metal contact points, conductive glides or casters, a drag chain, and ESD upholstery. The chairs, which have a 500-lb capacity, feature a saddle-shaped seat with a waterfall front to ensure even weight distribution and an executive-style seat-pan control. The contoured backrest is molded
to provide lumbar and kidney support, and a polished, five-point, aluminum base accommodates 3-inch dia dual-wheel ­casters.

BioFit Engineered ­Products

ESD Tester

The ELITE ESD Tester for wriststraps and footwear features a 30-VDC test circuit and virtual test resistance technology accommodating customizable test settings from 500 kΩ to 1 GΩ. A large LCD displays on-screen test resistance with a sliding scale to predict and prevent equipment failures. It stores more than 100,000 test results and 48,000 user tables, is network capable, needs no calibration, and can ship with optional HID reader and Wi-Fi capabilities.

Botron

GPS Receiver for Fieldmeter

The battery-powered GPS-R Receiver designed for the Smart Fieldmeter® Digital (SFD) Model RFP-05 identifies the user location and performs internal position logging. The unit attaches to the bottom plate of the SFD and stores field-strength information and time/date stamp on a removable memory card. The GPS-R provides 20-channel satellite tracking, 10-meter accuracy, and an update rate of 1 s. Software for position logging and PC streaming is installed. Map visualization of data points requires third-party mapping software.

EMC Test Design

Eco-Friendly ESD Carpet

The StaticSmart™ flooring line has been expanded with environmentally friendly Discovery ECO and Presidential ECO ESD Carpet Tiles for use in mission-critical areas. New features include expanded colors and patterns, a more robust ecoworx backing, cradle-to-cradle certification, CRI Green Label Plus certification for indoor air quality, and StaticSmart’s ESD protection and durability. Both types of carpet are manufactured using a conductive backing that is 100% PVC-free, recyclable, and made from recycled material. In addition, the yarn fibers contain a minimum of 25% recycled content. All StaticSmart ESD Carpet Tile are tested in accordance with ESD 7.1 and ANSI/ESD S-20.20 and AATCC 134.

Julie Industries

Injection-Molded Assembly Trays

A line of conductive trays for storing and transporting static-sensitive components and assemblies is molded in 0.085” thick plastic with surface resistivity below 10⁶Ω and tolerates temperatures to 60°C. Four versions are available: MS-Q11, eight sizes from 9" x 6.6" x 1.5" to 24" x 22" x 1.4"; MS-Q14, molded with eight permanent cells in varying sizes from 14" x 14" x 1.52" to 12.6" x 11.4" x 0.6"; MS-Q13, 14" x 5" x 2", which can be subdivided into smaller cells and features a lip to hang from a rack; and the MS-Q12, 18" x 13" x 1.6" with a removable grid that creates 70 cells measuring 1.7" x 1.7".

Fancort Industries

EM Coating

Nanovate™ EM Coating is high-permeability surface coating that provides low-frequency magnetic shielding. It can be applied to many polymers and composite surfaces. The direct coating shields complex geometries that are awkward to handle with shielding foils, and the application can be selective. It eliminates the need to incorporate shielding into monolithic molded parts, forming and shaping steps, the use of adhesives for bonding foils, and annealing of formed shielded foils. Nanovate also adds strength and stiffness to weaker substrates.

Integran Technologies

Broadband Amplifier

The 5213 1,000-W Amplifier covers the 200-MHz to 1,000-MHz frequency range and utilizes Class A/AB linear power devices providing a high third-order intercept point, large gain, and a wide dynamic range. RF input signal formats include CW/AM/FM/PM and pulse. The amplifier, controlled by front-panel keypads or remotely by RS-232/Ethernet or IEEE 488, is protected against VSWR, thermal overload, and over-current and -voltage. The 50-Ω input and output impedances are supported with Type-N input and 7/16-DIN output connectors.

Ophir RF

Dust- and Moisture-Resistant Enclosure

The Optima EH-case features either a HEPA filter on the front door with special gasketing to prevent dust ingress or a solid door with NEMA type gasketing. The swing handle incorporated into the design provides superior gasket compression. Both types can be adapted to meet acceptable EMC requirements. E-cases house EIA 19" wide subracks and chassis. The modular and stackable design has rigid front and rear aluminum bezels and rounded, extruded aluminum corner members and accommodates a range of configurations with various top, bottom, and side panel options. Accessories for doors, shelves, power, and cooling also are available.

Optima EPS, an Elma Company

Multiport BNC Connectors

Four-, six-, and eight-port right-angle units have been added to the company’s line of BNC connectors. The RoHS-compliant multiport BNC connectors are available in both filtered and unfiltered versions and 50-Ω or 75-Ω impedances. The specified operating frequency range is 0 to 1 GHz, tested and usable through 2.0 GHz. The connectors are of the classic throughhole/PC-mount configuration and provide solderable mounting tabs.

Regal Electronics

EMI Analysis Software for S-Parameters

EMI Analyst™ has added S-parameters into its library of computational models. The software uses a patented analysis method to model electronic circuits and provides analysis for conducted and radiated emissions and conducted and radiated susceptibility. It combines circuit theory, transmission-line theory, method-of-moments algorithms, and complex matrix techniques. The program models circuits, EMI filtering, cabling conductors and shields, and interconnected equipment. It supports several test standards including MIL-STD-461, RTCA/DO-160, FCC Part 15, and EN 55022. Typical applications include switching power supplies, serial data buses, and power inverters for industry segments such as military, automotive, avionics, consumer, medical, and industrial.

EMI Software

Extra-Large RF Shield

The 4933 RF Shield supports radiation and quality measurements for large radio transceivers, notebook PCs, and other electronic equipment. It combines a high shielding factor with easy access to the UUT. The 4933 attenuates signals from either outside or inside by a high degree. The attenuation, in conjunction with the RF connector, can be used to measure the radiation of the UUT in an EMC prequalification test without the need for a large anechoic shielded chamber. The shield comes with a solenoid lock and a control panel displaying the status of the lock and a USB interface.

Willtek, Wireless Telecom Group

Ceiling Ionization System

The Gemini G3 CleanRoom Ceiling Ionization System features intelligence to monitor and preemptively adjust to the changing condition of an environment. It operates in steady-state DC, pulsed DC, or the company’s patented Pulsed DC with Peak Reduction Technology, which reduces offset voltage and shortens discharge times. The system integrates with G3PM Ionization Management Software, providing real-time metering, datalogging of all events, and graphing of all metered values. E-mail notification of up to 15 monitored alarm conditions allows for immediate response to system performance.

SIMCO

Near-Field Scanning System

The EM-Isight Scanning System offers five or six axes of articulated robotic movement which can perform near-field analysis on PCBs, wireless handsets, and antennas. Measurements are made using an IEC-61967 magnetic probe feed into a standard spectrum analyzer. Features include effective correlation to standard EMC measurement methodologies, real-time data visualization tools, and complete distribution of the fields presented in a 3-D plot. 4-D measurements are achieved using X, Y, Z, and PHI movements. The dynamic range is dependent on environmental conditions and spectrum analyzer type; the integrated low-noise preamplifier provides an additional 28-dBm gain. The system can be located on a standard workbench and runs on Windows XP/Vista/Win7.

APREL Laboratories

Nonmetallic Resistive Wire

The newest additions to the line of Fibreohm™ Nonmetallic Resistive Wires are the FO102T6R, which has a linear resistance of 300 to 400 Ω/cm; and FO103T6R, offering a linear resistance of around 600 Ω/cm. Both wires possess outside diameters of 1.3 mm. Since Fibreohm wires interact minimally with electromagnetic fields, they are utilized in EM field probes, meters, and antennas. The wire is available on spools up to several hundred feet in length.

Marktek

Filtered Micro D-Sub Connectors

A line of smaller, lightweight EMI filtered micro
D-subminiature connectors is built to MIL-DTL-83513
and available fully RoHS compliant. The connectors have nine to 37 contacts and a variety of styles, terminations, and mounting options. They offer capacitance values to 4,700 pF, can be specified for selective line filtering, and provide an environmentally sealed contact area once mated. Micro D-sub connectors have an operating voltage to 100 VDC, dielectric withstanding voltage to 300 VDC, current rating of 3 A, and insulation resistance of 5 GΩ @ 100 VDC.

Spectrum Advanced Specialty Products

EMC Test Amplifier

The 7224 Amplifier can be used when testing to a range of susceptibility standards including Ford EMC-CS-2009, DO-160, MIL-STD-461, and T1.315-2001. Depending on the configuration, the 7224 provides up to 1,500 W and has an operating bandwidth of DC to 200 kHz and a 70 V/µs slew rate. It produces up to 30 A of 13.5 VDC with 2-V pk-pk of line disturbances from DC to 150 kHz and up to 160 V peak and 50 A peak. The 7224 features a small chassis size for benchtop or rack-mounted operation.

AE Techron

Ideally, EMC testing could be accomplished with one antenna, one amplifier, and one receiver. At least the receiver part generally can be achieved, and in some sports, one out of three is pretty good. Antennas and especially amplifiers perform best over limited bandwidths, a characteristic that complicates EMC test setups.

Part 1

In the early days just after the FCC released Part 15J to control those noisy digital systems, a company that wanted to make sure its product passed asked us to provide a complete and exhaustive data set. The system was complex with several modes of operation.

Where functional safety risks need to be controlled, relying solely on EMC testing is inadequate, no matter how high the test levels are cranked up. Further, many engineers and project managers are unaware of the functional safety and financial risks they incur by relying solely on EMC testing.

For a long time, spectrum analyzers and scanning receivers have been widely used in EMI laboratories. The technical capabilities of these instruments are similar to those of a classic stepped EMI receiver, with the primary exception being the dynamic range for quasipeak measurements.

In the semiconductor manufacturing industry, damage and yield losses attributed to the effects of static charges are well documented along with the determination of many of the specific causes.¹ If ESD controls are not implemented properly, ICs processed by handling equipment can be subjected to Charged Device Model (CDM), Field Induced Model (FIM), and Machine Model (MM) ESD failure modes. Here are the most serious failure modes we found with such equipment—ones that consequently have resulted in the largest amount of documented ESD damage.

Many types of signal generators and oscillators are used for EMC testing. Of them, lightning simulators are, without doubt, the most exciting. The maximum peak current that designers need to consider is about 200 kA with actual lightning-strike statistics showing an average of 20 kA and 140 kA exceeded 2% of the time.

A large majority of EMI problems, including both emissions and immunity, involve interference currents conducted into and out of the box via a power or data cable. These currents can be controlled by filtering or shielding, often through a connector.

All companies striving to survive and grow in today’s worldwide electronics industry recognize the value of performing design, development, and troubleshooting tests. These tests should be done early and often during a program to minimize overall costs to meet the formal EMC compliance requirements. It’s not necessary to test everything with every procedure every time the sample is tested, only those that may be a problem.

Large companies can afford a $10 to $30 million facility necessary for EMC qualification testing plus the additional expenses for the personnel to staff the operation. It could be argued that they can’t afford not to provide such facilities. On the other hand, small and medium-sized companies typically cannot justify their own fully equipped EMC qualification test facility…yet there still is a need to perform design, development, and troubleshooting tests.

RF signals appearing on wiring are common in virtually all installations of electronic equipment. Wiring acts as a receive antenna for radiated RF signals that induce currents in conductors; this may produce voltages in circuitry sufficient to impair operation.

EMC standards strike a balance between extremes. Emissions must be controlled, but equally, there is a need to harden a design against interference, whether from internal or external sources. Reducing emissions and their effects requires appropriate design effort but doesn’t necessarily mean a higher product price.

When the discussions turn to severe aerospace applications, it’s difficult to imagine one that is more severe than a launch vehicle/spacecraft combination. Here is a microwave systems platform operating at frequencies of 2,500 MHz and higher that has a rocket engine with 4,000^°F exhaust temperatures at one end, -452.5^°F (+4^°K) at the other end, 800g shock, 20 to 600g random vibration, and sound pressure levels at the location of the electronics packages that exceed 140 dBspl.

Amplification isn’t a difficult concept. You start with a small RF or microwave signal and make it into a large one. Ideally, you wouldn’t be able to distinguish between the two signals except by their size. Indeed, a power amplifier makes the input larger, but in doing so adds distortion.

Low-frequency signals appearing on the power lines—so what? The level is low relative to the primary power for an AC-powered device. And DC-powered systems are designed to function with wide variance in the input voltage, so why bother?

In the United States and many parts of the world, antennas are calibrated per the American National Standards Institute C63.5: American National Standard for Electromagnetic Compatibility—Radiated Emission Measurements in Electromagnetic Interference (EMI) Control—Calibration of Antennas (9 kHz – 40 GHz). A standard sets uniform methods, processes, and practices for the industry. Some standards may be mandatory while others are voluntary.

I’m working on a new system that does everything for everyone. I’ll take one of those, and one of those, and two of these. Do you have it from some other supplier in blue? Our sales/marketing department wants to offer it in blue. OK, wrap em up!

I’m working on a new system that does everything for everyone. I’ll take one of those, and one of those, and two of these. Do you have it from some other supplier in blue? Our sales/marketing department wants to offer it in blue. OK, wrap em up!

I’m working on a new system that does everything for everyone. I’ll take one of those, and one of those, and two of these. Do you have it from some other supplier in blue? Our sales/marketing department wants to offer it in blue. OK, wrap em up!

Cables—the nemesis of compliance, the antennas no one wants—often are the culprits or unwanted stepchildren in EMC testing. Controlling conducted emissions is an inherent problem that requires planning in the design phase. Selecting the appropriate control measures, installing them in an effective manner, and assessing if the EMC design conflicts with an operational requirement are integral to the product compliance.

They say that lightning doesn’t strike the same place twice. Wrong! The Empire State building has been struck thousands of times, so often that it was used as a test object during early lightning studies.

In the beginning of a new-product lifecycle, a request for quotation (RFQ) is issued. Potential bidders examine the RFQ, see a section on EMC requirements, and decide to use an outside test vendor for support. A Web search results in many excellent laboratories specializing in EMC.

Before an electronic product can be sold, it must comply with EMC standards. In general, EMC specifications attempt to ensure that a product's performance is compatible with its environment. Emitting signals that could disrupt operation of nearby equipment is not allowed. It's also important that the product continues to operate correctly when subjected to emissions from other equipment.

It's hard to imagine that a shielded enclosure could provide 3,000-dB RF attenuation, but based on the equations that define such values, it's not a problem. Shielding effectiveness is a function of frequency, and the higher the frequency, the greater the material attenuation. It just keeps rising.

Although it might appear that EMC shielding is a mature technology with little change and that application techniques are likewise stable, such is far from the case. Application requirements continue to change, and EMC suppliers are taking unusual measures to keep pace. These application briefs give some indication of the ways that EMC vendors are being creative to meet user needs.

EMC is all relative. For a given set of RF environmental conditions, at a given location, and at a specific relative instant in time, the equipment has EMC or the absence of failure. Change any of these conditions with respect to the equipment’s orientation and internal operation and an EMC failure may not occur because both the electromagnetic environmental (EME) disturbances and the equipment’s response to these disturbances are statistical in nature.

Traditionally, alloys of copper and beryllium (CuBe) provide the high levels of electrical conductivity for shielding and environmental protection, coupled with durability and low closure force. Applications include cabinets for telecommunications infrastructure, information technology, defense, and commercial and consumer electronics such as mobile phones and hand-held devices.

Air ionization is the most effective method of eliminating static charges on nonconductive materials and isolated conductors. Air ionizers generate large quantities of positive and negative ions in the surrounding atmosphere, which serve as mobile carriers of charge into the air.

We all want our test systems to have the smallest possible number of instruments and components. When you're conducting EMC studies across a wide range of frequencies, from the low megahertz region well into the gigahertz range, how many different antennas are needed?

The third edition of IEC 61000-4-3, published in 2006, has mandated changes in some key areas that may require the replacement of your radiated immunity test amplifier. Along with extending the test frequency range to
6 GHz and better defining the calibration of the uniform field, the standard requires verification of the power amplifier linearity and output harmonics. As a result, some existing systems may fail to meet the new requirements because the amplifier in use is being run near saturation, and consequently, the modulated field is distorted.

In electronic systems, wires and cables provide intentional circuit paths for power or signal currents to move from a source to a load and then return to the source. These current paths have the topology of a loop.

Hawaii provides the perfect setting for the many special features included in the 2007 IEEE International Symposium on Electromagnetic Compatibility July 8-13 in Honolulu. Not only is the theme this year East Meets West, but the IEEE EMC Society also will be observing its 50^th anniversary in the 50^th state with an impressive list of special activities such as a celebration luncheon on Friday (July 13).

Commercial and military/aerospace electronics manufacturers typically perform EMC tests on all new devices they design and develop. Some manufacturers also must do periodic checks on current production equipment to comply with new or changing regulations or military contracts.

There is no question that there are many products on the market that use digital electronics in their design. A brief trip through your favorite computer or electronics equipment store should eliminate any doubt in your mind.

Using cognitive-type radio features to help share frequency bands between various services is gaining popularity in the United States. Two of these features are transmitter power control (TPC) and dynamic frequency selection (DFS).

Some older engineers actually took a course in mechanical drafting that used triangles, T-squares, and holders with different grades of lead (graphite). Sketching 3-D drawings of boxes, cylinders, machinery, electric motors, and components was particularly challenging. That's when the class learned about vanishing points, the visual point where parallel lines converge and disappear. A good example is the highway that appears to become narrower as the distance increases.