According to a Memorandum of Understanding (MOU), the FCC, along with the U.S. Department of Health and Human Services (HHS) and the U.S. Department of Agriculture (USDA) will work together to develop and implement a joint Rural Telehealth Initiative intended to “address health disparity issues, resolve service provider challenges and promote broadband services and technology in rural areas of America.”

Under the terms of the MOU, the agencies have agreed to establish an interagency Rural Telehealth Initiative Task Force comprised of representatives from each agency and charged with developing a formal plan for the Initiative, consistent with the respective missions and authority of each partner agency. The Task Force will serve as a forum for the exchange of agency expertise, as well as relevant scientific and technical information, data and publications.

his article discusses the common-mode and differential-mode radiation from cables and presents the measurement results from the SMPS connecting wires.

If the fields generated by the forward current cancel the fields of the return current and no other circuits, or sources, or coupling paths are present, then the forward current equals the return current. In virtually any practical circuit, a different scenario takes place, as shown in Figure 2.

Î_D is referred to as the differential-mode (DM) current while Î_C is referred to as the common-mode (CM) current. The DM currents are usually the functional currents. They are equal in magnitude and of opposite directions. The CM (unwanted) currents are equal in magnitude and of the same direction (See [1] for the discussion of the CM current creation).

or 2020, TSMC is targeting to start mass production of its first 5 nm technology. Also, at this node FinFETs are the transistor architecture of choice. In this article, we will introduce FinFETs and their advantages over planar transistors. We will discuss some of the ESD protection design challenges when designing in a FinFET technology and give an outlook on the successors of FinFET.

his summer, the International Organization for Standardization’s Technical Committee in charge of standards for safety signs and symbols, ISO/TC 145, published a new Technical Specification, ISO/TS 20559 Graphical symbols – Safety colours and safety signs – Guidance for the development and use of a safety signing system.¹ This new international specification focuses on workplace safety sign systems. Yet many of its underlying concepts speak to various forms of safety communication meant to reduce risk in today’s world – including product safety labeling. In this article, we again go behind-the-scenes with insight from Geoffrey Peckham, the chairman of ISO/TC 145 and long-time member of the ANSI Z535 committee (as well as the founder of Clarion Safety Systems and the original author of this “On Your Mark” column).

According to ISO/TS 20559’s scope, it provides “recommendations and explanations on the practical application of safety signs to form a system of communication intended to reduce risk.” Safety signs and labels are basic communication tools used by organizations to lessen risk – but their risk reduction benefits are only fully achieved when these communication tools are designed correctly from the beginning, or, if already installed, replaced by signs and labels that meet the latest best practice industry standards. The new ISO technical specification, ISO/TS 20559, thoroughly describes the visual components that make up best practice “systems” of signage, making it an essential document for organizations to use to better manage risk.

As the quantity and variety of electronic equipment used in systems and installations continues to grow, EMC is becoming an increasingly important issue. Almost all my work on systems and installations since 1990 has been involved with items of equipment interfering with the correct operation of other items on the same site.

In 1990, variable speed motor drives using insulated gate bipolar transistors (IGBTs) and power field-effect transistors (PowerFETs) for high-speed power switching were very new, as were private mobile radio systems, and they both caused many problems with legacy electronic equipment. Since then, EMC standards and regulations in most countries have considerably improved the emissions and immunity of equipment, but at the same time, variable speed motor drives have constantly improved – by switching faster. Faster switching makes them more efficient, smaller and less costly, with the result that they are being used much more widely. Unfortunately, switching faster causes increased noise emissions at higher frequencies, increasing the possibilities for interfering with other equipment (see Figure 1).

he last thirty years have seen great strides in the deployment of communication network infrastructure. That growth is primarily due to the establishment of the IP protocol as a stable specification in the late 1970s. There have been many benefits to using an IP-based approach, and today all manner of different communications networks rely on its widespread adoption. That said, with an increasing emphasis on power-efficient communication for a growing variety of applications, there is a rising awareness that an alternative to IP might need investigation.

Since its formation, the TCP/IP protocol suite is responsible for creating the heart of the internet. The transport control protocol (TCP) deals with the transportation of data, the process of dividing up messages into packets and then reassembling them after transmission. The internet protocol (IP) takes care of the addressing and routing of the packets transmitted across a communications network of attached devices.

The TCP/IP protocol suite has seen many iterations to its specification over the years. Still, one of the guiding principles from its conception was that the endpoints occupied fixed positions and that their connections would remain unchanged. Increasingly, the networks in place today see that endpoints do move, and connections may be dropped and re-established depending on several criteria.

n more than ten years working in labs as an EMC engineer, the majority of devices and systems I have tested include two important elements that interact with each other, thereby allowing the equipment under test to work. Electronic boards and firmware. It is difficult to imagine an electronic board without firmware running in a microcontroller. Even a simple wall charger for batteries has integrated firmware to switch the behavior of the charger from constant voltage to constant current, and to switch into trickle charging or to begin the discharge process.

Over the years, I’ve come to think of firmware as the soul of every electronics board since, without firmware, almost every PCB would be “dead.” But because firmware is now so deeply embedded into the working mode of a device, what is the influence, if any, on a device’s EMC performances? Could, in theory, at least, a device using different firmware versions behave differently during EMC measurements? We’ll explore that question in this article.

ou understand how RF absorber works, appreciate why its pyramidal shape influences performance, can describe how it’s specified for performance, know how to select the correct length and shape for your application, and understand how it is manufactured and how the manufacturing process affects absorber quality. These are all great attributes of RF absorber that you must take into consideration when properly outfitting an anechoic chamber for EMC testing purposes. But have you also considered safety attributes, including the maximum power handling capability the absorber will need to meet in your application and also its flammability rating? The safety performance specifications of RF absorbers are just as important as the other attributes of RF absorber performance. Let’s talk about them next.

6. Use commonly available absorber lengths. Save money, speed delivery by choosing absorber in typical, off the shelf lengths.
7. Determine maximum power handling capability of absorber. Polyurethane absorbers are specified to withstand a maximum power of W/in2 of continuous wave (CW) incident field under room temperature with no additional forced airflow.
8. Manufacturing process impacts absorber quality. Find a computer controlled manufacturing process that begins with homogeneous blocks of polyurethane foam.
9. Use non-hygroscopic absorber. Maintain a stable absorber electrical property and RF reflectivity by reducing moisture, which affects electrical conductivity significantly.
10. Confirm RF performance verification testing. Ask how your supplier tests the absorber to verify performance reflectivity before shipment. Is each piece of absorber tested or sample tested one piece per batch? Is each piece serialized? Ask these questions protect your investment!

sk any experienced EMC test engineer or technician what one of the most frequently asked questions they get is and they’ll probably tell you something along the lines of the following:

“With the current broadband RF amplifier and antenna combination we have, what’s the highest field strength obtainable?”

The requestor is usually trying to find equipment that generates some enormously high field strength level to test their product, probably already knowing beforehand that the existing amplifier/antenna combo is not suitable.

The main reason the antenna/amplifier combo chosen is probably not adequate is because we usually only purchase what we need at the time. More power costs more money when it comes to broadband power amplifiers, so we typically only specify/buy to meet our current needs rather than what we may need in the future. This is a common cost-limiting approach practiced in most EMC test facilities.

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.

A balun transformer is used in antennas for matching the wideband impedance of the antenna to that of the amplifier. It is often the balun that determines the maximum amount of power that can be delivered to an antenna used for EMC testing purposes. Balun equipped antennas can also be used for radiated emissions testing.

Bilog antennas (ironically also portmanteau for biconical/log-periodic – BI-LOG) or just a plain biconical or plain log-periodic antenna must be protected against accidental damage during EMC compliance testing. A balun transformer, located at the antenna’s feed-point, limits the power-handling ability of the antenna because some of the power delivered to the antenna ends up as heat in the core and windings.

f you’re technically-minded and involved in EMC testing, then you’re probably well aware of all of the nerdy things involved in running an EMC test facility, properly outfitted with the best semi-anechoic chamber(s) and associated test equipment and cabling. To the exact letter of the law (i.e., standard), you already know how to set up and perform an accurate and repeatable radiated emissions or RF immunity scan. You know how ferrite tile and RF absorber works and which antenna(s) work best for each particular type of EMC test. You’re an expert at EMC testing but, when it comes to installing, tearing down, and moving an EMC chamber, you may not have a clear understanding of all of the non-engineering tasks that go along with such an important event.

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 bonded to the shield ground is used for testing the EUT.
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).

more thorough “in-between calibration cycle” check of the ESD simulator’s output waveform is something every EMC engineer and technician should consider.

n previous articles (references 1 and 2), we covered the basics of EMI filters and some of the common reasons why they often fail to provide the insertion loss performance we expect from them.

We learned that the most common reason why filters fail, (besides bad coupling paths and cable routing around the filter, improper bonding and grounding, and non-ideal placement within the equipment) is that EMI filters are, more often than not, specified using 50Ω termination impedances on both the line and load sides during the insertion loss measurement.

The 50Ω/50Ω filter insertion loss measurement method is easy to perform because most RF measurement apparatus (connectors, cables, receivers, etc.) are built around a characteristic impedance of 50Ω. However, we know that filter performance is highly dependent on termination impedance and that real-life circuits rarely contain such ideal 50Ω impedances. Therefore, the 50Ω insertion loss test method cannot be relied upon to accurately predict filter performance once installed in actual equipment.

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.

his article assumes the reader already has a basic understanding of how electromagnetic compatibility (EMC) shielding works. If you would like a refresher on EMC shielding, please see references 1 and 2, which describe how EMC shielding works in basic terms.

If you’re an electrical engineer and consider proper EMC shielding a mechanical only issue, please reconsider your position and keep reading.

f you’re performing commercial radiated and conducted emissions measurements strictly by the book, you will want to utilize a measurement receiver or spectrum analyzer that fully complies with CISPR 16-1-1. Briefly, this is what this means:

Note 1: The specifications in CISPR 16-1-1 apply to EMI receivers and spectrum analyzers. The term “measuring receiver” is also used in the EMC community and refers to both EMI receivers and spectrum analyzers.

Note 2: Often, the receiver specification under question depends on the frequency range of operation. In CISPR 16-1-1, there is one receiver specification covering the frequency range 9 kHz to 150 kHz (Band A), one covering 150 kHz to 30 MHz (Band B), one covering 30 MHz to 300 MHz (Band C), and finally one covering 300 MHz to 1,000 MHz (Band D). This article covers the 9 kHz to 1 GHz frequency range of operation and Bands A through D. Band E covers the 1 to 18 GHz frequency range of operation and has its own unique requirements.

Note 3: Specific requirements for measuring receivers used for military testing are found in MIL‑STD-461G and DEF STAN 59-411.

or some manufacturers, the cost of outfitting an entire full-compliance EMC test facility is not justified. These entities do not have enough sales volume, build unique one-off units, have tight margins, or lack the resources to staff an entire on-site, full-compliance test facility.

These types of manufacturers must rely heavily on the services of out-of-house, third-party test laboratories to properly test their products to confirm compliance before placing their devices on the market. The major problem with this approach, however, is that should the product fail at the test lab, the result will be delayed product shipments and missed revenue opportunities.

Utilizing early-stage in-house pre-compliance testing and sound engineering judgment, along with pre-compliance test data will boost confidence that the product will pass when it is eventually sent out-of-house for full compliance certification work. Learning in-house, using pre-compliance test methods as early as possible (when first prototypes are available), instead of at the end of the product development program (when attempting certification tests at the full-compliance test facility) will inevitably save manufacturers time and money. During final certification testing, there is immense pressure to meet your production release deadlines and being charged big dollars for lab time by the hour adds a whole other layer to that pressure. Having a product fail at this point in the process could be fatal to the project, especially if competitors get their product to market ahead of yours.

November 10
Ground Resistance Training Seminar

November 10-12
EMC Fundamentals

November 16-17
IEEE SPCE 2020

November 16-18
Advanced PCB Design for EMC & SI and Mechanical Design for EMC

November 16-18
Sensors Expo & Conference