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Minimize the susceptibility of noise sensitive circuits in seconds with electromagnetic shielding

How Does Shielding Work?

When an incident electric field traveling in the air hits a metal surface, the metal causes the penetrating field strength to decrease. The metal causes the field to be replaced with conduction currents that flow in the metal close to the surface. A very small (exponential decay) amount of the field does pass through, but for emissions, this is never a problem. The metal chassis serves as a shield. The field from all the radiating surfaces inside it are blocked and kept inside the box, with the only noise coming from the cables or wires that enter or exit the box and from holes made in the box.

If a metal enclosure is to be used, its shielding effect should be utilized. However, it is always better to reduce the noise inside the box than rely on shielding.

Grounding the Shield

The shield has the difficult job of providing a terminating or conducting surface for direct ESD hits, ambient fields, and internal fields, as well as noise carried on the cables entering and exiting the chassis. To do this well, the shield should be thought of as an RF conducting plane, with the least number of breaks and impedance’s between the source of the RF currents and the ground reference point.

Cables and Bypassing to the Shield

The PCB should have a large separate ground area tied to the enclosure shield, which serves as the ground for the I/O bypassing capacitors. These capacitors provide final filtering of system noise, but also are intended to filter noise picked on the cable outside the box. An RF path is required as the connection to the chassis.

How Can You Measure the Effectiveness of Shielding in Real-Time?

The use of component shielding and shielded printed circuit board (PCB) traces can avoid unpleasant problems late in a product design cycle. EMI shielding is one of the ways to minimize susceptibility to radiated spurious signals in noise sensitive circuits. Sometimes, radiating components must be located on both sides of the PCB, which may then necessitate shielding on both sides of the board as well. This will lead to a more costly, complicated board assembly process.

Visualization is the key to better understanding of a PCB’s electromagnetic performance. EMxpert shows the impact of the EMI shielding by board location and frequency. It also measures the effectiveness of EMI shielding by mapping near-field emissions generated by current flow on the surface of your board and helping diagnose any problems in real-time. The spatial comparison tool then facilitates immediate comparison between the shielded and unshielded solutions.

shielding

Example shows the emissions on the PCB before implementing the shield.

 

shielding-2

Example shows the emissions on the PCB after implementing the shield.

Why EMxpert Is Right For You

You can execute real-time analysis of your design, test multiple design iterations and optimize complex designs on your lab-bench in seconds at each stage of the design process.

You want to avoid the delays and set-up needed for far-field measurements in a chamber.

EMxpert not only require low CAPEX and zero OPEX, they also deliver significant ROI advantages.

Key Benefits

Test results in seconds
Easy to use
Compact and tabletop
Significant time-to-market acceleration
Dramatic increase in production
Substantial cost reduction

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Are you under time-to-market pressure because of the countless number of lengthy measurements in inaccessible anechoic chambers?

Tired of losing valuable project time waiting in line to test your designs in expensive anechoic chambers?

Do you want to test your design and performance quickly to accelerate project completion and delivery?

Are you under budget pressures?

Why did your product fail the compliance test in an anechoic chamber? Why didn’t you see this coming?

With EMxpert, in seconds and a fraction of an anechoic chamber cost you can easily:

  • Analyze your high speed, high power and/or high density/complexity PCB designs.
  • Visualize the root causes of potential EMC and EMI problems.
  • Find, characterize, and address unintended radiators or RF leakage.
  • Pinpoint the cause of a design failure even when the problem is intermittent.
  • Prototype, test, and optimize new designs, forms and components.
  • Test & optimize multiple PCB (printed circuit board) design iterations on your lab-bench.
  • Resolve EMC and EMI problems early in the design cycle
  • Display NFC antenna emissions

…all for a fraction of the cost of an anechoic chamber.

Calculate Your Savings

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  •   How does the EHX work?

    how-does-it-workThe EMxpert EHX consists of a patented scanner, a compact adapter, a customer-supplied spectrum analyzer and a PC running EMxpert software (EMxpert setup diagram). The EMxpert EHX measures the magnetic field (H-Field) in two orthogonal directions using H-field probes.

    The patented scanner is a passive device that couples the very-near-field emissions from the device under test. The measurements of these coupled fields are done with the spectrum analyzer and the adaptor synchronizes the spectrum analyzer and the patented scanner.

    The EMxpert software knows the insertion loss of each individual probe across the frequency range so it can apply compensation for the internal losses of the scanner.

    The software will also apply the antenna factor compensation that will result in accurate H-field data being displayed. Interpolation between probes is done by the software so that features smaller than the probe spacing can be resolved.

    The patented scanner consists of 1,218 H-field (magnetic) probes that operate between 150 kHz and 8 GHz. Probes are wide band but not very sensitive across this band thus they are very good at rejecting background noise.

    Each row and column on the patented scanner corresponds to a unique probe that is spaced every 7.5 mm into an electronically switched array, which provides an effective 3.75 mm resolution. Electronic switches enable the probes to sweep the entire board under one second.

  •   How does the EHX+ work?

    how-does-it-workThe EMxpert EHX+ consists of a patented scanner, a built-in adapter, a built-in spectrum analyzer and a customer-supplied PC running EMxpert software (EMxpert setup diagram). The EMxpert EHX+ measures the magnetic field (H-Field) in two orthogonal directions using H-field probes.

    The patented scanner is a passive device that couples the very-near-field emissions from the device under test. The measurements of these coupled fields are done with the spectrum analyzer and the adaptor synchronizes the spectrum analyzer and the patented scanner.

    The EMxpert software knows the insertion loss of each individual probe across the frequency range so it can apply compensation for the internal losses of the scanner.

    The software will also apply the antenna factor compensation that will result in accurate H-field data being displayed. Interpolation between probes is done by the software so that features smaller than the probe spacing can be resolved.

    The patented scanner consists of 1,218 H-field (magnetic) probes that operate between 150 kHz and 8 GHz. Probes are wide band but not very sensitive across this band thus they are very good at rejecting background noise.

    Each row and column on the patented scanner corresponds to a unique probe that is spaced every 7.5 mm into an electronically switched array, which provides an effective 3.75 mm resolution. Electronic switches enable the probes to sweep the entire board under one second.

  •   How does the ERX+ work?

    The EMxpert ERX+ consists of a patented scanner, a built-in adapter, a built-in spectrum analyzer and a customer-supplied PC running EMxpert software (EMxpert setup diagram). The EMxpert ERX+ measures the magnetic field (H-Field) in two orthogonal directions using H-field probes.

    The patented scanner is a passive device that couples the very-near-field emissions from the device under test. The measurements of these coupled fields are done with the spectrum analyzer and the adaptor synchronizes the spectrum analyzer and the patented scanner.

    The EMxpert software knows the insertion loss of each individual probe across the frequency range so it can apply compensation for the internal losses of the scanner.

    The software will also apply the antenna factor compensation that will result in accurate H-field data being displayed. Interpolation between probes is done by the software so that features smaller than the probe spacing can be resolved.

    The patented scanner consists of 1,218 H-field (magnetic) probes that operate between 150 kHz and 8 GHz. Probes are wide band but not very sensitive across this band thus they are very good at rejecting background noise.

    Each row and column on the patented scanner corresponds to a unique probe that is spaced every 7.5 mm into an electronically switched array, which provides an effective 3.75 mm resolution. Electronic switches enable the probes to sweep the entire board under one second when Level 1 is selected.

    The scanner is placed right under the Gorilla Glass. X/Y step motors move the scanner (1218 probes) for higher resolution scans under the Gorilla Glass. After placing the DUT on the Gorilla Glass, user can select from seven different levels of resolution (0.12 mm – 7.5 mm).

    The image on right is a representation of a 2 x 2 scan area on the scanner. At level 1, spatial scan is executed in real-time i.e. scanner doesn’t move. The data is collected by each probe that is placed in the center of each grid.

    At level 2, each grid is divided into four subgrids. Scanner first moves the orange dots and collects data from four subgrids. Scanner then moves to black dots and collects data from four subgrids. Scanner then moves to green dots and collects data from four subgrids and finally, scanner moves to purple dots and completes the scan.

    At each level, one grid is divided into four subgrids which means four measurement points. Level 7 is the highest resolution (120 microns) and the maximum number of measurement points in one grid can be 4,096.

Companies Who Trust EMxpert Products
What Our Customers Are Saying
“I’m an electronics technician with 30 plus years in the automotive electronics field. We could not afford to spend a lot of time and money at the end of the development cycle trying to fix EMC failures, especially at the expensive certified EMC labs that we used for final compliance testing. Our in house EMC lab was used for pre-compliance testing, we were not certified. For susceptibility testing we did: strip line, TEM cell, tri-plate and bulk current injection. This is where EMxpert comes in. When you’re doing susceptibility testing and there is an anomaly, it may not be apparent as to what part of the circuit is malfunctioning. For EMC, it is all about the up-front work that is done. Board layout and pre-compliance testing are very important. The farther into the design cycle you are, the more it will cost you to resolve it. If I had to describe EMxpert in one word it would be “up-front”. It’s like your headlights in the dark.”
Tom Livingston
Lectron
“I was very impressed with the capability of the EMxpert solution. We had spent several weeks investigating EMC issues related to our end customers product. We had information relating to the spectral component and amplitudes that were causing an issue, but needed to identify the location of the emission site. The EMxpert tool allowed us to perform spatial analysis and locate the site in a single day. The tool is effective and can save weeks of time and effort!”
Iain Lochhead
Semtech Director of Applications Support
“Where have you guys been for the last 5 years while we have struggled?” was the concluding comment from Robert… “We need one of these” was Robert’s conclusion.”
Robert Dmitroca
Senior Design Engineer - EMI
“I was very impressed with the capability of the EMxpert. The EMxpert tool allowed us to perform spatial analysis and locate the site in a single day. The tool is effective and can save weeks of time and effort!”
Director of Applications Support
Leading Semiconductor Manufacturer

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