For many years the ARRL Antenna Book has provided a table like this. Antenna analysis programs have adopted the values and they are widely used. However, the table is for the AM broadcast band. Since ground constants are anything but constant, the ARRL values are not suitable for HF where they are commonly employed.
The ARRL data originally appeared in the FCC publication Standards of Good Engineering Practice Concerning Standard Broadcast Stations in 1939. Inductivity is an obsolete term for dielectric constant. Conductivity is in EMU (10−14 = 1 mS/m).
1.8 3.7 5.3 7.1 10.1 14.2 18.1 21.2 24.9 28.5 ■ 86 119 64 128 55 133 49 137 42 142 36 148 33 152 31 154 29 157 27 159 ■ 60 40 43 47 36 51 32 54 27 58 23 63 21 66 19 68 18 71 17 73 ■ 20 3.6 17 5.0 16 5.9 15 6.8 14 8.0 13 9.3 13 10 12 11 12 12 12 13 ■ 13 .83 12 1.2 12 1.5 11 1.8 11 2.2 10 2.6 10 3.0 9.8 3.3 9.6 3.6 9.4 3.9 ■ 11 .44 9.5 .61 8.9 .72 8.4 .82 7.8 .96 7.3 1.1 6.9 1.2 6.7 1.3 6.5 1.4 6.3 1.5 ■ 4.7 .071 4.1 .10 3.8 .12 3.6 .14 3.3 .17 3.1 .20 3.0 .22 2.9 .24 2.8 .26 2.7 .28
George Hagn of SRI International developed these curves in the 1980s. The table lists permittivity followed by conductivity in mS/m for the ham bands. Use this interpolator to better represent your terrain. For best antenna model accuracy, use a ground probe to measure your soil. Otherwise use the Hagn values.
1.8 3.7 5.3 7.1 10.1 14.2 18.1 21.2 24.9 28.5 ■ 3.7 2.5 2.1 1.8 1.5 1.3 1.1 1.0 .95 .89 ■ 6.6 4.4 3.5 3.0 2.5 2.0 1.8 1.6 1.5 1.4 ■ 27 17 13 11 9.1 7.4 6.4 5.8 5.3 4.9 ■ 80 50 40 33 27 21 18 17 15 14 ■ 132 89 73 62 51 42 37 34 31 29 ■ 533 348 281 236 192 157 136 123 112 104
Skin depth in feet reveals the influence of subsurface soil on ground constants.
1.8 3.7 5.3 7.1 10.1 14.2 18.1 21.2 24.9 28.5 ■ 14 9.7 8.2 7.1 6.0 5.1 4.6 4.2 3.9 3.7 ■ 6.7 5.3 4.7 4.3 3.8 3.4 3.2 3.0 2.8 2.7 ■ 1.8 1.4 1.2 1.1 1.0 .89 .81 .77 .73 .69 ■ .62 .49 .44 .40 .36 .32 .30 .29 .27 .26 ■ .40 .31 .28 .25 .22 .19 .18 .17 .16 .15 ■ .15 .12 .11 .099 .089 .080 .074 .070 .067 .064
Loss tangent indicates the relative importance of conductivity and permittivity. When loss tangent exceeds 1, an antenna is more sensitive to changes in conductivity than permittivity.
Saltwater permittivity and conductivity are constant over HF but vary with salinity and temperature. In nonpolar, open ocean, permittivity ranges from 70 to 80 and conductivity from 3000 to 6000 mS/m. This map shows ocean conductivity but does not resolve coastal values, which vary with local freshwater discharge. Use Deep Dive in this map to find conductivity for seawater along the U.S. coast or saline water inland (divide µS/cm by 10 for mS/m). To calculate permittivity, use this program with coastal salinity and temperature from this map. 75 and 4500 mS/m are reasonable generic values for open ocean.
Freshwater permittivity is constant over HF but varies with temperature:
°C °F Permittivity 0 32 88 5 41 86 10 50 84 15 59 82 20 68 80 25 77 78 30 86 77
Freshwater conductivity is constant over HF but varies with temperature and widely with location, e.g., 4 to 29 mS/m for individual Great Lakes and 20 to 100 mS/m for major rivers. Use Deep Dive in this map to find local U.S. values (divide µS/cm by 10 for mS/m). Absent local data, 15 mS/m is a reasonable generic value for a lake.
0.137 0.475 50 98 146 ■ 307 113 166 115 22 171 16 191 14 206 ■ 205 37 112 38 13 80 10 92 9.1 101 ■ 60 2.6 34 3.0 10 16 9.1 20 8.6 24 ■ 29 .41 19 .55 8.9 5.0 8.4 6.8 8.2 8.2 ■ 20 .19 14 .27 6.1 2.0 5.9 2.7 5.8 3.3 ■ 6.3 .024 5.2 .039 2.7 .37 2.6 .51 2.6 .62
I used the Messier soil model to extrapolate Hagn generic ground constants at 2 MHz to LF/MF and constants at 30 MHz to VHF.
G. H. Hagn, "Ground Constants at High Frequencies (HF)" mistitled "HF Ground and Vegetation Constants" in Proceedings of Third Annual Review of Progress in Applied Computational Electromagnetics, Monterey, CA, 24–26 March 1987.
H. W. Parker and Withan Makarabhiromya, "Electric Constants Measured in Vegetation and in Earth at Five Sites in Thailand," Special Technical Report 43, SRI Project 4240, Stanford Research Institute, Menlo Park, CA, December 1967. Data source for the Hagn generic curves.
88–108 MHz