Soil Dielectric Properties

This table, in a slightly different format is found in: Arthur R. von Hippel, ed.: “Dielectric Materials and Applications”, M.I.T. Press, Cambridge, MA, 1954. It was posted on the NEC-LIST, and I foolishly forgot to note the poster’s name, who should be credited

The temperature for all tables is 25C. The tables are structured cut and paste into a text file or Excel spreadsheet.

Sandy Soil – Dry, 2.18%, 3.88%, 18.8% Water
Loamy Soil – Dry, 2.2%, 13.77% Water
Clay Soil – Dry, 20.9% Water
Magnetite Soil, Dry, unknown, 4.8%, 11.0% Water
Amplifilm (Bentonite + binder)

Sandy Soil – Dry

Frequency	E/Eo		Tan d
1.0E+02 3.420E+00 1.960E-01
1.0E+03 2.910E+00 8.000E-02
1.0E+04 2.750E+00 3.400E-02
1.0E+05 2.650E+00 2.000E-02
1.0E+06 2.590E+00 1.700E-02
1.0E+07 2.550E+00 1.600E-02
3.0E+08 2.550E+00 1.000E-02
3.0E+09 2.550E+00 6.200E-03
1.0E+10 2.530E+00 3.600E-03

Sandy Soil – 2.18% Water

Frequency	E/Eo		Tan d
1.0E+02 3.230E+00 6.400E-01
1.0E+03 2.720E+00 1.300E-01
1.0E+04 2.500E+00 5.600E-02
1.0E+05 2.500E+00 3.000E-02
1.0E+06 2.500E+00 2.500E-02
1.0E+07 2.500E+00 2.500E-02
3.0E+08 2.500E+00 2.600E-02
3.0E+09 2.500E+00 3.000E-02
1.0E+10 2.500E+00 6.500E-02

Sandy Soil – 3.88% Water

Frequency	E/Eo		Tan d
1.0E+03 1.500E+03
1.0E+05 5.000E+00 1.900E+01
1.0E+06 4.700E+00 1.750E+00
1.0E+07 4.500E+00 3.000E-01
3.0E+08 4.500E+00 3.000E-02
3.0E+09 4.400E+00 4.600E-02
1.0E+10 3.600E+00 1.200E-01

Sandy Soil – 18.8% Water

Frequency	E/Eo		Tan d
1.0E+03 3.425E+03
1.0E+04 3.670E+02
1.0E+06 2.000E+01 4.000E+00
1.0E+07 2.000E+01 3.500E-01
3.0E+08 2.000E+01 3.000E-02
3.0E+09 2.000E+01 1.300E-01
1.0E+10 1.300E+01 2.900E-01

Loamy Soil – Dry

Frequency	E/Eo		Tan d
1.0E+02 3.060E+00 7.000E-02
1.0E+03 2.830E+00 5.000E-02
1.0E+04 2.690E+00 3.500E-02
1.0E+05 2.600E+00 3.000E-02
1.0E+06 2.530E+00 1.800E-02
1.0E+07 2.480E+00 1.400E-02
3.0E+08 2.470E+00 6.500E-03
3.0E+09 2.440E+00 1.100E-03
1.0E+10 2.440E+00 1.400E-03

Loamy Soil – 2.2% Water

Frequency	E/Eo		Tan d
1.0E+03 2.100E+00
1.0E+04 1.800E+01 1.600E+00
1.0E+06 6.900E+00 6.500E-01
1.0E+07 4.000E+00 4.500E-01
3.0E+08 3.500E+00 6.000E-02
3.0E+09 3.500E+00 4.000E-02
1.0E+10 3.500E+00 3.000E-02

Loamy Soil – 13.77% Water

Frequency	E/Eo		Tan d
1.0E+03 8.490E+03
1.0E+04 9.700E+02
1.0E+07 1.450E+01 1.300E+00
3.0E+08 2.000E+01 1.600E-01
3.0E+09 2.000E+01 1.200E-01
1.0E+10 1.380E+01 1.800E-01

Clay Soil – Dry

Frequency	E/Eo		Tan d
1.0E+02 4.730E+00 1.200E-01
1.0E+03 3.940E+00 1.200E-01
1.0E+04 3.270E+00 1.200E-01
1.0E+05 2.790E+00 1.000E-01
1.0E+06 2.570E+00 6.500E-02
1.0E+07 2.440E+00 4.000E-02
3.0E+08 2.380E+00 2.000E-02
3.0E+09 2.270E+00 1.500E-02
1.0E+10 2.160E+00 1.300E-02

Clay Soil – 20.9% Water

Frequency	E/Eo		Tan d
1.0E+03 7.800E+03
1.0E+04 1.000E+03
1.0E+07 2.160E+01 1.700E+00
3.0E+08 2.000E+01 5.200E-01
3.0E+09 1.130E+01 2.500E-01

Magnetite Soil – Dry

Frequency	E/Eo		Tan d
1.0E+06 1.090E+00
1.0E+07 1.090E+00
3.0E+08 1.090E+00 2.500E-02
3.0E+09 1.005E+00 2.900E-02

Magnetite Soil – (unknown)

Frequency	E/Eo		Tan d
1.0E+02 3.950E+00 4.100E-02
1.0E+03 3.750E+00 2.900E-02
1.0E+04 3.620E+00 2.200E-02
1.0E+05 3.520E+00 1.700E-02
1.0E+06 3.500E+00 1.500E-02
1.0E+07 3.600E+00 1.200E-02
3.0E+08 3.500E+00 1.800E-02
3.0E+09 3.500E+00 2.200E-02

Magnetite Soil – 4.8% Water (rho=2E5 ohm-cm)

Frequency	E/Eo		Tan d
1.0E+06 1.200E+01 9.000E+00
1.0E+07 1.000E+01 1.000E+00
3.0E+08 9.000E+00 1.200E-01
3.0E+09 8.300E+00 2.200E-01

Magnetite Soil – 11.0% Water (rho=2E4 ohm-cm)

Frequency	E/Eo		Tan d
1.0E+07 3.000E+01 4.000E+00
3.0E+08 3.000E+01 2.000E-01
3.0E+09 3.000E+01 3.200E-01

Amplifilm – Dry (Bentonite Clay with organic binder)

Frequency	E/Eo		Tan d
1.0E+03 4.320E+00 2.200E-03
1.0E+04 4.300E+00 1.900E-03
1.0E+05 4.300E+00 1.700E-03
1.0E+06 4.300E+00 1.700E-03
1.0E+07 4.290E+00 1.800E-03

More data, from a NEC-LIST post on 30 May 2000 by Prof Duncan Baker (, citing “TAI Inc Consuletter International”, Vol. 6, No. 5, Earth Constants by Peter N Saveskie:

Earth Type                                  Conductivity   Permittivity
Sigma (Mhos/m) Epsilon
Poor 0.001 4.0 - 5.0
Moderate 0.003 4.0
Average 0.005 - 0.01 10.0 - 15.0
Good 0.01 - 0.02 4.0 - 30.0
Dry, sandy, flat (typical of coastal land) 0.002 10.0
Pastoral Hills, rich soil 0.003 - 0.01 14.0 - 20.0
Pastoral medium hils and forestation 0.004 - 0.006 13.0
Fertile land 0.002 10.0
Rich agricultural land (low hills) 0.01 15.0
Rocky land, steep hills 0.002 10.0 - 15.0
Marshy land, densely wooded 0.0075 12.0
Marshy, forested, flat 0.008 12.0
Mountainous/hilly (to about 1000 m) 0.001 5.0
Highly moist ground 0.005 - 0.02 30.0
City Industrial area of average attenuation 0.001 5.0
City industrial area of maximal attenuation 0.0004 3.0
City industrial area 0.0001 3.0
Fresh water 0.002 - 0.01 80.0 - 81.0
Fresh water at 10.0 deg C (At 100 MHz) 0.001 - 0.01 84.0
Fresh water at 20.0 deg C (At 100 MHz) 0.001 - 0.01 80.0
Sea water 4.0 - 5.0 80.0 - 81.0
Sea water at 10.0 deg C (to 1.0 GHz) 4.0 - 5.0 80.0
Sea water at 20.0 deg C (to 1.0 GHz) 4.0 - 5.0 73.0
Sea ice 0.001 4.0
Polar ice 0.00025 3.0
Polar Ice Cap 0.0001 1.0
Arctic land 0.0005 3.0

Comments from George Hagn (

The ITU-R Recommendation on Ground Constants is in error in the HF band. It is not possible to have no dispersion in both the conductivity (sigma, in S/m) and the relative dielectric constant (epsilon r) across the same span of frequency. The ITU-R data show constant values across the HF band, and the ITU-R conductivity starts to increase with increasing frequency at exactly 30 MHz. The Hilbert transform pair relate the real and imaginary parts of a complex variable that satisfies certain conditions. The complex relative permittivity (epsilon r complex = epsilon r prime – j epsilon r double prime) satisfies these constraints, and therefore the effective relative dielectric constant (epsilon r prime, the real part) and the conductivity (part of epsilon r double prime) are deterministically related for any given soil at a given volumetric moisture content. The relationship is given in the literature as the Kramers-Kronig relationship, and an ACES paper a year ago or so gave an example of this for a semiconductor. The K-K relationship implies that if one of the terms has no dispersion, the other term must have maximum dispersion. For example, if the relative dielectric constant of sandy soil is very low (e.g., 3.5), then the conductivity has its maximum dispersion (with conductivity increasing by over an order of magnitude across the HF band). I have demonstrated this with measurements with my open-wire line (OWL) kit many times (e.g., VOA site at Rhodes, Greece; Eglin AFB, FL, etc.). Therefore, dont rely on the ITU-R data for HF ground “constants.” I am in the process of providing ITU-R Study Group 3 with revised curves for the Recommnedation so that it can be corrected. Anyone interested in more on this, please contact me at my email address.

The conductivity starts out with the DC conductivity, which is due to the ions in the moisture that is “free water” and not “bound water.” As the frequency increses past about 1 MHz for most soils, the conductivity starts to rise. The term that does decrease monotonically with increasing frequency is the term epsilon r double prime, the loss term. It does so for frequencies up to about 1.5 GHz. The loss term then starts to increase (as the absorption of the water molecules start to dominate the loss process over the ionic conductivity that was dominant at lower frequencies on down to DC. The conductivity goes through a maximum value at about 17 GHz, the frequency at which epsilon r prime and epsilon r double prime are equal, and then starts to decrease for frequencies above about 17 GHz. The exact frequency of the maximum varies with soil characteristics, but it is a frequency below the absorption line at 22.235 GHz for pure deionized water.

Leave a comment

Your email address will not be published. Required fields are marked *