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An Insider Blog from Leaders on EMC & Radar Engineering


On August 22, 2019, the FCC issued an enforcement advisory in regard to several companies' interference with the Federal Aviation Administration's terminal doppler weather radar station in San Juan, Puerto Rico. 

斗地主达人According to investigations under the Enforcement Bureau, interference was caused by outdoor wireless devices, in particular, those operated by wireless internet service providers (WISPs) to provide point-to-point broadband connectivity.  

On October 25, 2019, the FCC published 47 CFR Parts 1 and 27 [WT Docket No. 18–120; FCC 19–62], Transforming the 2.5 GHz Band, in the Federal Register Daily Journal of the United States Government

This document, which serves as a final rule, revises the regulatory framework surrounding the 2.5 GHz band in order to make more mid-band spectrum available for next generation wireless services, including 5G. Amendments 27.14 (u) and (v) and 27.1204 are effective beginning November 25, 2019. The rest of the document will go into effect on April 27, 2020.   

斗地主达人The requirements delineated in sections 27.14 (u) and (v) and 27.1204 now include amended collections subject to the Paperwork Reduction Act of 1995 (PRA), Public Law 104-13. These revisions will be submitted for review, and the FCC encourages comment on the modified information.

For more information, you can view the official document . 

 

 

PCB Design Principles to Reduce Crosstalk

Posted on October 21st 2019 by

斗地主达人The PCB designer is no stranger to EMC issues, especially the issue of crosstalk. 

Crosstalk is any undesirable signal transfer between communication channels or traces within a PCB. Put simply, crosstalk occurs when one trace's signal overpowers another trace's signal. The aggressor, whose signal is louder or stronger, can keep the victim trace from communicating information properly, causing the board to work incorrectly. In addition, the victim trace will often try to "raise its voice" or strengthen its signal in response, thus acting like the aggressor trace. 

Because re-designing PCBs due to noncompliance is frustrating, it is in the designer's best interest to incorporate crosstalk mitigation techniques into the design cycle before submitting the product to a testing laboratory. 

If there's one thing that PCB and EMC design have in common, it's that these designs are often left until the very end of the product design cycle. As with EMC design, waiting until the last moment to consider PCB design can be costly, time-consuming, and stressful, especially when dealing with high-speed PCB design. 

FCC-Upcoming TCBC Fall Workshop

Posted on October 9th 2019 by

The Telecommunications Certification Body Council (TCBC) is hosting its Fall 2019 Workshop November 12 - November 14, 2019 at the Marriott Inner Harbor in Baltimore, Maryland。 Registration closes on November 5, and the TCBC urges interested parties to hurry and book their rooms! 

This three-day-workshop event will discuss the following topics:

  • FCC, ISED, and NIST updates
  • Standards updates 
  • Roundtable discussions 
  • Presentations on various topics, including 5G  

Review of MIL-STD-704F

Posted on October 7th 2019 by

First released in October of 1959 to replace MIL - E - 7894, MIL-STD-704 delineates the standards for compatibility between aircraft power systems and utilization equipment. Initially, MIL-STD-704 only accounted for 28 Vdc and 115/200 Vac at 400 Hz originating from a three-phase, four-wire source. Over time, various revisions were made to the standard by establishing new requirements; adding voltage ranges; correcting erroneous information; creating new test methods; and releasing change notices.

The latest revision, Revision F (issued in 2004), is the current MIL-STD-704 standard. Below is a review of this standard according to its latest revision.

In a recent letter to FCC Chairman Ajit Pai, chairwoman of the Committee on Science, Space, and Technology Eddie Bernice Johnson expressed concern over the FCC’s proposal for an emissions limit of -20 dBW for the 24 GHz band, citing studies from NASA and NOAA that conclude that at an out-of-band emissions limit of -20 dBW, activity in the 24 GHz band would interfere with weather data. The studies claim that, instead, the emissions limit for 24 GHz should be -52.4 dBW.

The Biggest Questions About 5G Answered

Posted on September 22nd 2019 by

First introduced in 2009, 4G fueled the smartphone movement, which revolutionized the way we view technology. Instead of a device that could only take photos, make calls, and send messages, the phone became an essential part of life. It became our GPS and our source for internet and entertainment; but most importantly, it became a convenient one-stop-shop by combining various forms of technology. With 4G, we could access information wherever and whenever we wanted. Now, a new generation of wireless technology has people talking: 5G.

On August 26, 2019, the FCC issued a Protective Order, which establishes procedures to protect the confidentiality of information in regards to a recent petition to amend Parts 25 and 101 of the Commission’s Rules to Authorize and Facilitate the Deployment of Licensed Point-to-Multipoint Fixed Wireless Broadband Service in the 3.7 - 4.2 GHz band (RM-11791) as well as a request to modify coordination procedures in bands shared between the fixed service and fixed satellite service (RM-11778).

When engineers begin designing their products, electromagnetic compatibility is usually the furthest thing from their minds。 EMC testing is often left until the very end of the design cycle because designers aren’t educated on EMC design (the process of planning and preparing for EMC testing) and techniques for mitigating electromagnetic interference—or they simply dread the subject。

According to a survey conducted by Irdeto Global Connected Industries, 80 percent of organizations’ IoT devices have experienced a cyberattack within the last 12 months.

In response to Executive Order 13859, on August 9th, 2019, the National Institute of Standards and Technology (NIST) released U.S. Leadership in AI: A Plan for Federal Engagement in Developing Technical Standards and Related Tools.

On August 6, 2019, Canada’s Department of Innovation, Science, and Economic Development (ISED) released a draft of the Supplementary Procedure for Assessing Radio Frequency Exposure Compliance of Portable Devices Operating in the 60 GHz Frequency Band (57 GHz - 71 GHz). SPR-003 delineates general test methods to assess compliance with power-density exposure limits described in RSS-102 for portable devices operating in the 60 GHz frequency band.

FCC Fights for 5G Rollout

Posted on August 12th 2019 by

The latest generation of cellular technology, 5G, promises greater speed, reduced latency, larger bandwidth, higher resolution, and a capacity 1,000 times greater than that of 4G. Despite these advantages, however, 5G has had various hiccups along the way to rollout due to rumors that this generation of cellular technology will cause adverse health effects.

 

 

Electromagnetic interference (EMI) is a disturbance that causes the malfunction of electronic equipment。 While some EMI does not pose a significant threat—such as static noise on the radio—EMI that affects critical infrastructure, military assets, and medical equipment can pose economic and, sometimes, life-threatening risks。

For instance, in 1989, EMI triggered by a geomagnetic storm disturbed the Hydro-Quebec power system. Within 92 seconds, the entire system collapsed, leaving six million people without power. This type of disaster can be extremely dangerous, as witnessed on July 13th, 2019 when New York City suffered a blackout, leaving 73,000 people without power in this summer’s intense heat. While there were no injuries or deaths reported, many were left without air conditioning, others stuck in elevators and traffic jams.

To prevent disasters like this, it is imperative to mitigate the susceptibility of electronic equipment to EMI. In order to accomplish such a task, engineers should be aware of the three types of EMI sources: inherent, natural, and man-made sources.

Inherent EMI

Inherent sources of EMI are those caused by the thermal agitation of electrons flowing through circuit resistance. Thus, with this type of EMI, a device disrupts its own functioning. Radio static is on example of inherent EMI.

Natural EMI

Natural sources of EMI are those caused by natural events, such as lightning, solar magnetic storms, rain particles, and solar radiation. These sources of EMI do not pose a serious threat to electrical or electronic equipment, but they can affect older radio frequency communication equipment. According to NOAA, however, solar geomagnetic storms, like the one described above, can cause such issues as:

  • Placing extra drag on satellites in low-earth orbit
  • Modifying the path of radio signals
  • Creating errors in positioning information provided by GPS
  • Disrupting GNSS and
  • Producing geomagnetic induced currents (GICs) in power grids and pipelines.

Man-Made EMI

Man-made sources of EMI are those produced by electrical or electronic equipment, such as powerlines, welders, generators, and computer circuits。 Often, man-made EMI occurs when two signals are within close proximity to each other, and when not properly shielded, cause malfunction or disruption。

A sub-category of man-made EMI is intentional EMI (IEMI), which is often referred to as electronic warfare. Military assets and critical infrastructure are primary targets for such attacks and can face such threats as high-altitude nuclear electromagnetic pulse, E-bombs, EMP cannons, and high-power microwave weapons.

Thus, it is imperative that such assets are properly shielded from EMI using conductive materials, which block electromagnetic emissions and reflect/absorb them. EMI shielding can be accomplished with EMI shielding gaskets and conductive silicones.

EMI Shielding

Shielding gaskets are mechanical devices used to protect electronics from EMI. Traditionally, they were formed from metal sheets of aluminum, copper, or steel. These sheets, however, were not malleable, and under sealing pressure, would deform and allow leakage to and from other electronic devices.

Today, shielding gaskets are formed from flexible metal screens, metal wires, metal foams, and coatings made of metallic ink. Some equipment, however, requires additional shielding benefits for such conditions as hot or cold weather—and for these purposes, conductive silicones are more appropriate.

Conductive silicones, or particle-filled silicones, are produced using silver, silver-aluminum, silver-copper, silver-glass, and nickel-graphite。 Engineers might choose conductive silicones over traditional shielding gaskets because silicones resist sunlight, water, and a wide range of temperatures。

For instance, ruggedized touchscreens use conductive silicones to ensure environmental sealing in extreme weather conditions as well as to provide electrical conductivity. Additionally, unlike some traditional EMI shielding gaskets, conductive silicones won’t stretch or become deformed during gasket cutting.

When deciding which type of metal or material to use for EMI shielding, consider the following:

  • Do you need protection against electric fields, magnetic fields, or both?
  • What is the device’s frequency range?
  • How difficult will the coating process be?
  • What are the shielding standards?
  • In what environment will the device be used?
  • How much corrosion resistance will be needed?
  • What is the cost for the materials?

EMI shielding is imperative for protecting equipment from interference, ensuring products work accordingly, and keeping users safe. To confirm that electrical or electronic equipment is compliant with FCC standards, it is important to test your products with an EMC testing lab, such as Rhein Tech Laboratories, Inc. We provide design and testing services with an emphasis on EMC/EMI, including Shielding Effectiveness Testing. To learn more about our process, check out our How We Do It page.

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