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Accuracy Plots & Faraday Cage Interference Shielding

To achieve high-precision dielectric data, users must understand analyzer accuracy boundaries and eliminate external environmental interference.

1. How to Read Impedance Accuracy Plots

Eynocs specification sheets present performance boundaries using logarithmic plots:

  • Axes: The vertical axis denotes impedance magnitude (|Z| in Ω\vert{}Z\vert{}\space in\space \Omega), while the horizontal axis displays frequency (ff in Hz).
  • Constant Capacitance Diagonals: Capacitive samples follow diagonal lines across the plot according to:

|Zc|=12πfC′\vert{}Z_c\vert{} = \frac{1}{2\pi f C’}

  • Evaluating Operating Points: Trace your sample’s expected capacitance diagonal across your target frequency range. Verify that the operating line remains inside acceptable uncertainty contours (e.g., 0.5%,1%,or 5%0.5\%, 1\%, or\space 5\%).

2. Normal Precision (NO-PR) vs. High Precision (HI-PR)

Normal Precision: Suited for standard impedance, conductivity, and general capacitance measurements.

High Precision: Critical when measuring low-loss dielectrics where phase errors or small dissipation factors (tan⁡δ\tan \delta) must be accurately resolved.

3. Faraday Cage & Grounding Best Practices

Electrostatic fields from mains wiring, power supplies, and ambient electronics distort sensitive impedance sweeps.

  • When to Shield: A Faraday cage is mandatory for low-capacitance samples and low-loss materials (where dissipative current is extremely small relative to reactive capacitive current).
  • Proper Protective Earthing (PE): Connect the metal enclosure of the Faraday cage directly to laboratory Protective Earth (PE) via a low-impedance connection.
  • Avoid Common Pitfalls: Do not ground over painted or oxidized enclosure surfaces. Do not arbitrarily bridge signal ground and protective earth, as this induces ground loops and introduces extra system noise.

This information, together with additional practical recommendations and measurement considerations, is covered in the complete guide for optimal measurement conditions with Eynocs Analyzers

Optimal Measurement Conditions Guide