Accurate Evaluation of Magnetic- and Electric-Field Losses in Ground Systems

The efficiency of ground-based antennas is highly determined by the power dissipated in the ground plane, which can be separated into H-field and E-field losses. In this paper, a new approach is presented for the separation of ground losses that is based on Joule's law. It is theoretically vali...

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Bibliographic Details
Published in:IEEE antennas & propagation magazine 2007-12, Vol.49 (6), p.58-70
Main Authors: Dorado, Luis A., Trainotti, Valentino
Format: Magazinearticle
Language:English
Subjects:
Antennas
Bands
Computational modeling
Conductors
Current distribution
Earth
Equivalence
Frequency
Ground plane
Grounds
Magnetic losses
Magnetic separation
Mathematical models
Physics computing
Screens
Skin
Soil
Soil (material)
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Summary:The efficiency of ground-based antennas is highly determined by the power dissipated in the ground plane, which can be separated into H-field and E-field losses. In this paper, a new approach is presented for the separation of ground losses that is based on Joule's law. It is theoretically valid at any frequency. Nevertheless, some simplifications can be applied in the low-and medium-frequency bands, where the Earth's soil behaves like a good conductor. In the analysis, the antenna's ground plane has been divided into two zones: a) the artificial ground plane, where a radial-wire ground screen was used; and b) the natural ground plane or bare soil, up to a circular boundary a half wavelength from the antenna's base. In order to avoid overestimating the penetration of fields in the artificial ground plane, the previous theory has been extended by introducing the concept of effective skin depth. The monopole's nonzero equivalent radius effect has been taken into account by means of a modified current distribution. Also, the case of short top-loaded antennas has been treated. H-field and E-field losses have been analyzed by means of equivalent resistances and computed numerically as functions of frequency in the LF and MF bands for different antenna dimensions, ground screens, and soil physical conditions. Some results have also been obtained by Moment-Method simulations.
ISSN:1045-9243
1558-4143
DOI:10.1109/MAP.2007.4455847