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Industrial and Manufacturing

  • Evaluating absorbers for power loss and ratio of power transmitted (RTP)

    Close-up of a futuristic electronic circuit board with various electronic components.

    Carefully choosing high-performance EMI suppression materials is crucial for high-speed data transmission, factory automation and other applications where signal transmission is important. Inherent material properties such as permeability and permittivity are common metrics for evaluation. But material performance can also be conducted by power loss and transmission attenuation power ratio (RTP). These methods are often easier and faster, and can be performed either in the plant or in the field. This is why 3M publishes performance values for power loss and for RTP to help experts quickly and clearly evaluate materials for EMI performance to identify the appropriate material for specific applications.

    • Image showing diagram of VNA setup for power loss measurement using microstrip line.

      Power loss and RTP

      Power loss and RTP measurements are both important and valid for evaluating material performance in an electronic system

      Power loss

      This measurement of absorbed or dissipated energy in material is based on the formula: Ploss = Pin – Pout.

      Power loss is typically measured using a microstrip line with a particular sample size. An example of the test arrangement is shown. Power loss can be calculated in relative parameters, also known as S parameters following the simple equation: Ploss =1-|S11|2-|S21 |2, where, S11 represents power reflected from the test specimen, and S21 represents power transmitted through the test specimen. Both S11 and S21 are measured using a vector network analyzer.

    • Image showing IEC standard RPT calculation with sample setup.

      Ratio of power transmitted

      RTP measurements represent the ratio between the signal transmitted and the signal entering the absorber. While power loss essentially shows the amount of power lost during transmission, RTP measures the amount of power that reaches its destination.

      According to International Electrotechnical Commission (IEC) standards IEC6233-2, RTPs calculated using the equation shown in the figure at right.

      Here, absorber material is also placed over a microstrip line and S parameters S21 and S11 are measured (by VNA) but board design and sample dimensions are defined by IEC6233-2 standard.

      Both power loss and RTP can help professionals streamline their system procurement and assembly, as well as help ensure performance in a wide range of complex electronic environments and qualify control of received materials. They can:
       

      • Assure that every material lot falls within specs.
      • Simplify measurements vs. material properties such as permeability and permittivity.
      • Perform testing quickly and easily with limited training required for personnel.
    • Image of 3M EMI Absorber AB8000 Series, designed for high-temperature near-field applications from 300 MHz to 4 GHz.

      A full range of EMI absorbers from 3M

      Our selection of EMI absorbing and flux field directional materials includes the 3M™ EMI Absorber AB8000 Series, a high-temperature absorber for near-field applications from 300 MHz to 4GHz. Its transmission attenuation power ratio has been tested and measured in accordance with section 4.3 of IEC62333-2.

      3M can recommend the best test methods for your needs.

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