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I am trying to understand how to design an inductor that has constant parameters over a wide range of frequencies. Especially over high frequencies because I want to use them for impulse testing which have a characteristic frequency around up to 100kHz.

  • What exactly makes the inductance of a real inductor change at diferent frequencies?
  • What is the effect of the core in this dependency? (With or without iron core, for example.)
  • What has to be considered in the design to minimize the skin effect so as to have a low ESR?

Additional info:

To illustrate this, I have five different inductors for which I have performed Ls and Rs measurements on an Agilent E4980A RLC meter:

enter image description here

All of these inductors have a decently constant Ls value from 50 Hz to 300kHz, but their ESR behavior differs.

enter image description here

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  • \$\begingroup\$ Why is inductor #2's inductance at 300 kHz in volts? Are you sure you were always measuring series resistance? \$\endgroup\$
    – Andy aka
    Commented Oct 30, 2023 at 13:06
  • \$\begingroup\$ @Andyaka My bad, that is supposed to be μH instead V. But yeah pretty sure I was measuring Ls and Rs since those are the output values of the LCR meter \$\endgroup\$
    – Santi Ospina
    Commented Oct 30, 2023 at 14:37
  • \$\begingroup\$ Wide band inductors might look a little like this. \$\endgroup\$
    – periblepsis
    Commented Oct 30, 2023 at 22:07
  • \$\begingroup\$ @periblepsis Do you have any idea on why this design is helpfull for wide-band applications? Thank you though! \$\endgroup\$
    – Santi Ospina
    Commented Oct 31, 2023 at 12:09
  • \$\begingroup\$ @SantiOspina You may want to start by reading "Radiation Field of a Conical Helix", by J. S. Chatterjee. And then read his paper called "A Wide-Band Oscillator Using a Conical-Helix Tuning Inductor", published the following year. \$\endgroup\$
    – periblepsis
    Commented Oct 31, 2023 at 21:46

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