Troubleshooting tools: scanners and current probes

Article By : Arturo Mediano

The EMxpert system lets PCB engineers find, characterise and address unintended radiators or RF leakage areas.

« Previously: 10 views from the IEEE EMC 2016

EMSCAN is a Canadian company that designs Fast Magnetic Very-Near-Field measurement tools. Its real-time low-cost desktop tools that help you isolate the sources of emissions on PCBs.

While visiting the EMSCAN booth (Figure 1), I met with Erkan Ickam to see the company's products. I'm quite familiar with these scanners because I have two models in my lab.

__Figure 1:__ *The near field scanners from EMSCAN: RF antenna testing solutions (left) and PCB EMI solutions (right).*

For PCB engineers, the EMxpert system lets you find, characterise and address unintended radiators or RF leakage areas. You can pre-test and resolve EMC/EMI design problems in real-time, getting insights about why designs fail. All measurements occur in the near field. You can use EMxpert for NFC (near-field communication) antenna testing. I was able to see the new EHX system for ultra-high speed (>2 GHz) PCBs with scan range up to 8GHz. The EHX+ features built-in spectrum analyser and you can select 120 microns resolution level based on the density of your board design.

In the video below, I recorded the EMxpert working in real time. You can see the spectral and spatial scans of the PCB on top of the scanner. Both 2D and 3D views are available, which lets you clearly identify the origin of emissions.

For antenna designers, EMSCAN's the RFX2 Antenna Pattern Measurement System solves the expensive and time-consuming measurement problem of performing troubleshooting measurements in a large chamber. You can easily check gain, efficiency, pattern characteristics, etc. on the bench for applications as cellular, Wi-Fi, Bluetooth, LTE, MIMO, RFID and GPS.

Langer EMV Near field probes and instruments for immunity testing

The E1 Immunity Development System from Langer EMV is a useful tool for designers interested in troubleshooting EMI/EMC susceptibility problems at the PCB level (Figure 2). The system is small and fits easily on your bench.

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__Figure 2:__ *E1 Immunity Development System from Langer EMV.*

Dipl. Ing. Lars Gläßer, from Langer in Germany, could explain how the system works using a demo board with some relays, digital circuits and analog circuitry.

With the E1, you have access to a generator to apply burst and ESD disturbances into your PC board. In that way causes of burst and/or ESD area quickly identified allowing the designer to solve the causes of the interference.

In the video below you can see a short demo using the SGZ-21 burst generator injecting transients in the ground system of the demo board (common mode for the victim circuits).

Current probes from Fischer Custom Communications

Fischer Custom Communications, Inc. (FCC) designs, develops and manufactures specialised transient protection devices, RF test and measurement instruments, and EMP test systems. The company is best known for its current probes. Company president David Fischer explaining the products included in the exhibit this year, focusing on current probes.

EMI/EMC problems are usually related to the control of current path and current probes are the most important tool to "see" that current. It's those common-mode currents that are so often the cause of EMI problems.

Current measurements are made by placing the current carrying conductor within the "sensing" window of the probe and measuring the probe’s output voltage with an RF detector or instrument. The probes are calibrated so the voltages measured are converted to current over the frequency range of interest.

From the many probes in the booth, I found interesting for this blog to show you the F-57 Universal Current Probe (Figure 3).

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__Figure 3:__ *The F-57 current probe from Fischer Custom Communications.*

This probe, with its RF N connector, has a 3-dB bandwidth of 100 kHz to 500MHz. That covers a typical range of frequencies where both emissions and susceptibility problems appear. Transfer impedance (ZTΩ) is 1 with a maximum current in RF (CW) of 2A. This is a robust for your EMI/EMC troubleshooting activities.

Next: Compliance test tools: LISNs and antenna masts »

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