The website purportedly set up and run by “WiFi Freedom USA” falsely claims to administer the FCC’s program and that it can provide consumers with free devices and services under the program.

The FCC’s Emergency Broadband Benefit Program was established earlier this year to provide qualified consumers with discounts of up to $50 per month on their broadband services, as well as a one-time $100 discount on the purchase of a laptop, desktop, or tablet computer from participating providers.

The FCC is encouraging those who may have provided personal information through the WiFi Freedom USA website to visit https://www.IdentityTheft.gov.

apacitors are among the most commonly used components on a circuit board. With the ever-increasing number of electronics devices (from mobile phones to cars), there has been a growing demand for capacitors. Covid 19 pandemic has disrupted the global supply chain of components from semiconductors to passive components, and capacitors have been in short supply¹.

A discussion on the subject of capacitors could easily become a book or a dictionary. To start with, there are different types of capacitors such as electrolytic, film, ceramic capacitors, and so on. Then, within the same type, there are different dielectric materials. There are also different classes. As for physical construction, there are two-terminal and three-terminal capacitor types. There’s also an X2Y type capacitor which essentially is a pair of Y-capacitors packaged in one². What about supercapacitors? The fact is, if you sit down and start reading the capacitor selection guide of major manufacturers, you could easily spend a day!

ne early contributor to semiconductor ESD research was Jack Smith of Lockheed, who was fond of stating that all ESD damage is, in the end, thermal [1]. This is because there is always conversion of electrical field energy into heat, into mechanical motion of atoms. Even in the case of voltage overstress, field energy knocks atoms out of place at defect sites, thus linking field energy to the heat equation on a microscopic scale at least.

Jack liked to start a presentation on, say, metal heating with a universal equation (Figure 1) and go from there to specific cases.

In this article, our approach will be to examine some ESD heating cases where the analysis becomes simple enough to derive significant insight and overview, without necessarily going into an extensive calculation or computer simulation. Indeed, we’ll refer to some computer simulation work that was done with much-increased efficiency due to those insights.

ing Solomon’s secrets may be hidden in a shard of copper slag.

How, you may ask, would we know anything about a biblical King from a blacksmith’s slag—his metallurgical waste pile?

Going deeper than you or I might, down into the slag’s elemental composition, archaeologists have discovered evidence in the last decade that King Solomon may have had smiths skilled enough to build the Kingdom of Judah described in the Bible. A baptismal basin that stood on twelve bronze bulls. A hall of cedar. A magnificent ivory throne. Who knows what could have been possible?

A vision of history illuminated by a simple tool: the XRF gun.

his is the fifth article in a series of articles devoted to the design, test, and EMC emissions evaluation of 1- and 2-layer PCBs that contain AC/DC and/or DC/DC converters, and employ different ground techniques [1-4]. In this fifth article, we are still focused on the DC/DC power converter board (2-layer PCB). In this article, we evaluate the implementation of several EMC countermeasures and present the conducted emissions results, for both voltage and current methods, according to CISPR25 Class 5 limits.

In the first article in the series, [1], we defined the overall design problem. The second article, [2], focused on the details of the 2-layer DC/DC converter design. The third article [3] presented the radiated and conducted emission results from the baseline design, which did not contain any EMC countermeasures. The results showed multiple failures in both radiated and conducted emissions. The fourth article [4] presented a systematic approach to improve these radiated failures by populating the PCB with optional EMC countermeasures on component pads that have already been designed into the PCB layout and showing their impact on the radiated emissions. The EMC countermeasures are illustrated in Figure 1 as purple dashed boxes labeled EMC-A through EMC-F.

This article discusses the impact of these countermeasures on the conducted emissions results using both the voltage and the current methods. The voltage method results are discussed first, followed by the current method results. The article concludes with a brief description of what can be expected in the next article in the series.

harged Device Model (CDM) discharge events are the major root cause for electrostatic Discharge (ESD) failures in a modern, automated production and test environment. The CDM stress testing is well established for product qualification. It simulates the possible charging of a packaged device during automated handling followed by the discharge stress event which is caused by contacting one pin with e.g., the grounded test equipment. However, due to the nature of the occurring air discharge, the CDM test shows a low reproducibility with respect to the resulting discharge pulse. The related standard [1] considers this fact by allowing a peak current variation of more ± 20 % during the tester verification process on special verification modules for pre-charge voltages below 250V. The test of real devices can show even a higher variation depending on the package and pin type. This lack of discharge repeatability can result in an expensive re-design if the device under test (DUT) does not meet the required CDM failure threshold. Thus, there is a demand for an improved repeatability stress method.

he focus of these “On Your Mark” columns is visual safety communication related to equipment, machinery, and component parts – especially the symbols and content that make up on-product labels, warnings, and instructions. While we specifically hone in on these elements, they cannot – and should not – operate in a vacuum. That’s because they’re one, intertwined component in a comprehensive product safety strategy; looking at them separately could be detrimental to the safety of the product user and to the liability risk of the manufacturer. Here, let’s explore the key components to keep in mind for your product safety strategy – from risk assessment to safety labels and manuals – and some of the ways that they all work together to improve safety and reduce risk.

“Their main duties can be summed up simply as: provide a safe product, instruct in its safe use, and warn of its hazards,” says Angela Lambert, who works with product safety teams on a regular basis through her role heading standards compliance at Clarion Safety Systems. “Executing on this throughout the design and manufacturing process, however, is much more nuanced, and mandates looking at key areas of product safety in a systematic way. This helps to ensure consistency and will situate a manufacturer in the best potential position should a liability claim arise.”

According to Lambert, these areas include:

errites are frequency dependent components used to attenuate unwanted high frequency RF signals that can cause failure of emission and immunity compliance tests. There is an endless variety of form factors for ferrites, including toroidal shaped cores, clamp-on cable shells, surface mount beads, leaded through hole components for installation on printed circuit boards, and other custom shapes and sizes for use in many different types of applications.

First, determine the frequency range that needs to be attenuated. This frequency may be obtained after having performed pre-compliance testing or perhaps discovered unexpectedly during full-compliance, run for record types of compliance testing. The former situation allows for successful integration of the ferrite component into the design prior to release to production of the end product. The latter situation usually involves adding the ferrite suppression device as an after-thought, usually attaching a clamp-on type of ferrite device to external cables to suppress the RF signal and obtain passing results.

6. Installation can add significant costs to your project, so look for absorber that is rigid and stable in dimension, typically made through a molding process, which are easier to install, and uniform looking.
7. Are the materials water resistant, to continue working in humid environments? A closed cell structure composition provides a water resistant environment.
8. Are the materials fire retardant? Protect your testing environment with materials that meet stringent fire retardant requirements
9. Be confident that you adhere with growing environmental concerns and prioritize your selection for materials that are environmentally safe.
10. And finally, insist that your absorber has a quality assurance manufacturing process that checks and audits each and every piece of absorber (as opposed to “batch” monitoring) before it is installed into your test environment.

onducted RF immunity is a test method that subjects the equipment under test (EUT) to a source of disturbance comprising electric (E) and magnetic (H) fields, simulating those coming from intentional RF transmitters. These disturbing E and H fields are approximated by the E and H near-fields resulting from the voltages and currents caused by the test setup described in standards such as IEC 61000-4-6.

To ensure test repeatability and not cause either over or under testing, standards such as IEC 61000-4-6 have specific requirements for how the test is conducted. A small portion of the standard describes the requirements for generating the fields using a RF signal generator and power amplifier. If you’re performing commercial conducted radiated immunity tests strictly by the book, you will want to utilize a radio-frequency (RF) signal generator and power amplifier combination that fully complies with IEC 61000‑4‑6.

5. Some modulations, if required for the test application, would require a higher power amplifier. Example: When performing an 80% AM modulation test, the amplifier needs to have 5.1dBm of margin to accommodate the peak.
6. Antennas, Cables, DUTs & Rooms have cumulative VSWR. It is best to allocate for some power margin.
7. Consider the application, is this a single test or will it be used repetitively.
8. Consider your desired RF connection types and locations optimal for your application.
9. Also consider if automation will be used so the appropriate remote capability is included.

ntennas used for EMC testing possess several characteristics which make them ideal for use in a fast-paced, production-like EMC test environment. This article will briefly describe what these characteristics are, starting with the most important parameter – antenna factor.

Antenna factor units are dB/m for E-field antennas. Make sure the antenna you choose is provided with a table of the antenna factor versus frequency because in order to convert (in software) the measured voltage at the antenna terminals into the actual field strength at the antenna, you have to add the antenna factor and cable attenuation (also a function of frequency). Here is an important equation to remember in case you need to troubleshoot a problem with your measurement system not measuring correctly:

E (dBµV/m) = V (dBµV) + Antenna Factor (dB/m) + Cable Attenuation (dB) – Preamp gain (dB).

Note 1: Ignore preamp gain if a preamp is not used.

re you considering the purchase of an EMC chamber for in-house testing? If so, what factors should you consider for determining if the investment is a wise choice or if the continued utilization of a third-party test facility is the better option? For some, the decision is easy. The volume of products they intend to develop that require EMC testing is so low that the cost to bring EMC testing in-house is clearly not justified. For others, they may have a lot of new products in development (or plan to) and taking them to an outside EMC testing facility on a regular basis is not only costly, it is inconvenient and time-consuming. For those in this latter group, trying to decide if they should bring EMC testing in-house is not always a straight-forward decision.

7. MIL STD and DO-160 chambers can be Semi-Anechoic or Fully Anechoic. Standards require the absorber have a minimum absorption of 6dB from 80MHz to 250MHz and 10dB above 250Mhz. A table with a conductive top is used for testing the EUT and is bonded the shield ground.
8. CISPR 25 chambers are fully lined on walls and ceiling, contain a similar table with metal lining on top, and must pass the Long Wire Test or the Reference Site Method test to meet the Standard.
9. Reverb chambers rely upon the reflectivity of the walls and an internal movable paddle to reflect generated signals and increase the value of V/m generated from the transmit antenna.
10. Information needed to design a reverb chamber is the lowest frequency, the test volume, maximum V/m, and standard to be tested to (MIL STD, DO, ISO).

lectromagnetic Interference (EMI) filters (also called a power line filters), are passive, frequency selective, bi-directional (two-port) networks comprised of inductors, capacitors, resistors and ferrites.

These low pass filter devices are often thought of as just components whose sole purpose is to suppress unwanted emissions emanating from the electronic devices they’re installed in, so these products can pass regulatory compliance emissions tests.

Don’t overlook the fact that EMI filters can also be used to prevent unwanted RF noise (such as electrical fast transient burst, conducted RF, and some surges) from entering susceptible devices, especially if the EMI filter is combined with proper device shielding in a kind of “belt and suspenders” approach to electromagnetic compatibility. In this case, EMI filters help make RF susceptible devices more rugged in their surrounding environments, if these environments happen to also be heavily polluted with RF noise. EMI filters come in handy when the electronic products they are paired with must comply with national and international standards for both emissions and immunity (susceptibility).

6. When testing for avionics at 400Hz power, filters should also use Power Factor Correction Coils. This ensures that high reactive currents at 400Hz are neutralized.
7. Larger power filters (above 200 Amps) should have an option to be floor standing. This ensures that most of the weight is on the stand rather than on the shielded wall.
8. Protection performance for HEMP/EMP filters should be according to MIL-STD-188-125 or IEC 61000-4-24. These are the preeminent standards used today for specifying conducted Point of Entry protection.
9. When protecting a facility against HEMP/EMP, it is crucial to indicate if the filters will be installed inside or outside the protective shield. Only one side of the filter has the protective elements; the protection side must be that which is exposed to the threat.
10. When using electronic power sources connected to filters, the source should have a transformer in its output circuitry. This minimizes unwanted interaction with filters.

pectrum analyzers are expensive pieces of equipment that should be handled with care, especially when it involves applying signals to the RF input. Some new users may not know what “care” means and how to go about ensuring the spectrum analyzer they’re using is protected from overloading and damage. The intent of this article is to describe how not to blow up your spectrum analyzer. Those new to the subject of spectrum analyzers and measurement receivers may first want to review references 1 through 3 which cover some of the basics concerning spectrum analyzers and measuring receivers in general.

It is usually the mixer that is most susceptible to damage, followed by some of the other components identified in Figure 1.

RF Input

The RF input port (usually located on the front of the spectrum analyzer) is where the signal desired to be measured goes. Before applying any signal to this port, it is prudent to first ask ourselves, “What can we do to this input? and “What can we apply here safely?”

hether you’re trying to get a product through safety approval from one of the many Nationally Recognized Testing Laboratory’s (NTRLs) or having full compliance EMC testing performed at an accredited or non-accredited third-party laboratory or an internal in-house test facility, it’s imperative for successful completion of the project that as a compliance engineer or technician leading a product certification effort, you trust but verify the work of these other entities. For the remainder of the article, we’ll call these other entities “service providers.”