Simplified calculation of ground losses in low- and medium-frequency antenna systems

Calculations of ground losses are paramount in obtaining the best performance of a monopole antenna in the low- (LF) and medium-frequency (MF) bands. Ground losses are usually computed numerically, due to difficulties in the mathematical formalism. The novel approach here permits obtaining simple an...

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Bibliographic Details
Published in:IEEE antennas & propagation magazine 2006-12, Vol.48 (6), p.70-81
Main Authors: Dorado, Luis A., Trainotti, Valentino
Format: Magazinearticle
Language:English
Subjects:
Antenna measurements
Antennas
Conductivity measurement
Current distribution
Density
Electrical resistance measurement
Ground plane
Grounds
Magnetic analysis
Magnetic fields
Mathematical analysis
Mathematical models
Performance loss
Power dissipation
Soil
Soil (material)
Studies
Surface resistance
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Summary:Calculations of ground losses are paramount in obtaining the best performance of a monopole antenna in the low- (LF) and medium-frequency (MF) bands. Ground losses are usually computed numerically, due to difficulties in the mathematical formalism. The novel approach here permits obtaining simple analytical expressions for ground-loss calculations that can be useful for determining the behavior of the ground plane. As a first approximation, the monopole antenna is placed on a perfect electrically conducting (PEC) ground plane in order to obtain the antenna current distribution and the near magnetic field, taking into account the non-zero-radius effect of the monopole. Next, the near magnetic field is used to determine the surface-current density on the ground plane below the antenna. This is divided into two zones: (1) the artificial ground plane, where either a radial-wire ground screen or a metallic layer is used to increase the soil's conductivity; and (2) the natural ground plane or bare soil up to a circular boundary a half wavelength from the antenna's base. The power dissipation is calculated from the artificial and natural ground-plane surface-current densities, and the ground-plane loss resistance is obtained. Also, an effective conductivity is defined as a measure of the ground plane's effectiveness, and the cases of quarter-wave monopoles and short top-loaded antennas are analyzed. Some results are validated by means of numerical computations and moment method simulations
ISSN:1045-9243
1558-4143
DOI:10.1109/MAP.2006.323345