FCC Investigates Amazon, Others for Marketing Wireless Signal Jammers

The U.S. Federal Communications Commission (FCC) is reportedly investigating Amazon and a number of other online retailers and drone technology companies for their alleged sale of illegal radio frequency devices.

The FCC’s actions align with an investigation conducted by NBC News that found more than a dozen different companies marketing devices for sale that interfere with licensed communications systems by sending out competing radio signals…

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Do Measurements Validate Simulations?

Or Do Simulations Validate Measurements?

By Bruce Archambeault

expect the title of this article might raise a few eyebrows! It is very common for people doing simulations to make a measurement of a similar set up to validate the simulation. This is a reasonable precaution since modern simulation tools will give a very accurate answer to whatever question it is asked. The real issue is did the tool user understand the problem well enough to capture the important features, and did the user understand the tool well enough to use it correctly.

However, we usually do not expect a measurement to be validated. After all, measurements are a great emotional comfort! I have seen many test laboratories claim measurement uncertainty in the 1.5 to 2 dB range. However, whenever I ask an experienced EMC test person how well they might expect to correlate between two different laboratories, I often get a response that anything better than 8 dB is ok, and certainly, I have never been told that better than 6 dB is expected! This tells me what the ”real” laboratory accuracy is. And this is when all the equipment is functioning to specification.

Functional Safety: Overview and Methods

A Guide to Understanding Functional Safety Basics

By Michael Hamilton

unctional safety (FS) is a complex, and oftentimes a confusing, subject even for those familiar with product safety and certification. With good reason, there are numerous functional safety standards that apply to various product types and applications, each with their own nuanced requirements. Some end-product standards specify one or more FS standards to use for embedded controls, while others leave it open to interpretation.

In short, FS evaluations are required whenever a control—regardless of whether it is electronic, pneumatic, hydraulic, or another type—is used to achieve safe operation of a product. Depending on the application specifics and the end-product standard, functional safety may only encompass hardware controls or include both hardware and software.

Thermal Runaway Energy Release as a Function of the State of Charge

By May Yen, Artyom Kossolapov, and Francesco Colella

Introduction

Advancement in lithium-ion (Li-ion) batteries has resulted in them being the power source of choice in consumer electronics. These types of batteries have the advantage of high power and energy densities. As the chemistry of Li-ion batteries advances, so does their capacity and energy density. The higher the energy content and the smaller and tighter the internal components, the higher the potential risk, magnitude, and consequences associated with battery failure events.

How Manufacturers and Retailers Can Collaborate to Provide Quality Products and Conduct Effective Recalls

Working Together Can Improve All Aspects of Safety

By Kenneth Ross

everal months ago, I chaired an online seminar discussing the relationship between manufacturers and retailers in handling product safety issues.¹ In addition, years ago, when I was an in-house lawyer, and more recently as a product safety lawyer, I’ve had a number of experiences with retailers that sold my company’s or my client’s products. This article will address some of the issues discussed during that online seminar, as well as some of my individual experiences in dealing with retailers.

In addition, I will discuss a new product safety initiative just announced by Amazon which offers a useful summary of techniques that can be utilized by manufacturers and retailers to make safer products and engage in more effective recalls.

Image Theory: Radiation From Hertzian Dipole Above Ground Plane

By Bogdan Adamczyk

his article presents the derivation of the radiated far fields from a Hertzian dipole antenna above the ground plane using image theory.

1. Hertzian Dipole Antenna

An electric dipole, often referred to as a Hertzian dipole, shown in Figure 1, consists of a short, thin wire of length l carrying a constant current  positioned symmetrically at the origin of the coordinate system and oriented along the z-axis.

Figure 1: Hertzian dipole

Ideally, the wire is infinitely short; practically, a wire of the length l << /50 ( = wavelength) can be considered a Hertzian dipole.

The far field of a Hertzian dipole has only a θ component (in a spherical coordinate system) and is given by [1].

Voltage to Current Correlation for CDM Testing

By Lena Zeitlhoefler, Theresa Lutz, Friedrich zur Nieden, Kai Esmark, and Reinhold Gärtner for EOS/ESD Association, Inc.

New Approaches for CDM Testing

It is now well known that testing for CDM ESD evaluation is becoming a bigger challenge. Previously, (In Compliance Magazine, March 2021) Capacitively Coupled TLP (CCTLP) was described as an alternate approach. It offers many advantages compared to the standardized field-induced CDM setup according to the JS002 standard [1]. Testing of a package, bare die, or wafer is enabled with high reproducibility. The failure correlation between CDM and CCTLP has been investigated based on peak current stress levels and not by a charging voltage level [2]. If testing with an alternative CDM method as CCTLP is done to reproduce JS002, the CDM charging voltage must be transferred into peak current levels.

Device and Tester Capacitance

A measure for the severity of the CDM stress is the effective capacitance C_eff of a device [3]. C_eff characterizes the amount of exchanged charge between DUT and test setup at a specific stress level (e.g., V_CDM) in a specific testing environment.

Products can be categorized with respect to C_eff in an FICDM setup because of the direct relation to the peak current for a given test voltage, as described in [4].

PRODUCT Showcase

Using RF Monitoring Probes to Troubleshoot Transient Failures

By Dr. Min Zhang

ur previous column (see “Using a Near-Field Probe to Troubleshoot Transient Failures,” In Compliance Magazine, February 2024) introduced a valuable technique for troubleshooting electric fast transient (EFT) failures at the PCB level. However, in large systems, such as big cabinets housing numerous electronic components, employing the near-field probe method can be time-consuming and, depending on the voltage level, potentially unsafe (for instance, when dealing with high-voltage circuits requiring isolation). In such scenarios, an alternative approach is necessary. This “Troubleshooting EMI Like a Pro” column presents a technique suitable for use in such situations.

Large systems typically consist of interconnected PCBs or modules linked by cables. Placing RF current probes at various wire connection points enables the tracing of current flow during transient events. These RF current probes must be terminated to the 50-ohm impedance of an oscilloscope. Transient events vary in type, with their frequency response indicated by rise time. For instance, electrostatic discharge (ESD) exhibits the fastest rise time (sub-1 nanosecond), while electric fast transients typically have a rise time of about 5 nanoseconds. Both types suggest unpredictable RF current flow, especially in low‑impedance systems. However, engineers often have a reasonable estimation of the route. Therefore, multiple RF probes can be utilized to trace the current flow.

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