Ferrite 43 Material Core Loss

Updated VNWA Complex Permeability Measurements

Dominant Ferrite 43 material transformer loss is magnetizing admittance core loss.

Given the following inputs:
μi = Initial Permeability
Lμi = uH at Initial Permeability
F = Frequency MHz
μ' μ" = Complex Permeability at F, from Fair-Rite 43 MATERIAL Permeability (CSV) file

Core Admittance can be computed using the following equations:
L = Lμi * (μ' / μi)
Xs = 2π * F * L
Q = μ' / μ"
Rs = Xs / Q
Z = Rs + i * Xs
Y = 1 / Z

Magnetizing admittance is the real part of the complex admittance Y. Fractional loss equals load admittance divided by sum of load and core magnetizing admittance. The equation for a 50 Ohm load is:

fractional loss = 0.02 / (0.02 + Re(Y))
dB=10*log10(fractional loss)

Magnetizing Admittance Core Loss for a range of frequencies can be computed and plotted through a range of initial permeability inductance values.

Magnetizing Admittance Core Loss as a function of Inductance at Initial Permeability

Reciprocal of Magnetizing Admittance as a function of Inductance at Initial Permeability

Example using One Turn on a Fair-Rite 2843010402 Core

VNWA Measurement

Analysis

Inductance at initial permeability ~= 3 uH
Measured Insertion Loss at 13.5 MHz = 1.39 dB
Mismatch loss for SWR 1.56 = 0.22 dB
Measured Insertion Loss minus Mismatch Loss = 1.17 dB
Plotted Magnetizing Admittance core loss for Initial permeability of 3 uH ~= 1.3 dB

Example using Four Turns on a Fair-Rite 2843010402 Core

VNWA Measurement

Analysis

Inductance at initial permeability ~= 44 uH
Measured Insertion Loss at 13.5 MHz = 0.14 dB
Mismatch loss for SWR 1.20 = 0.036 dB
Measured Insertion Loss minus Mismatch Loss = 0.104 dB
Plotted Magnetizing Admittance core loss for Initial permeability of 44 uH ~= 0.1 dB

Three and Seven Turn 1:1 Transformers on a FT82-43 Toroid

FT82-43 3T:6T Transformer