# Resistively loaded antennas for ground-penetrating radar: A modeling approach

## Détails

ID Serval

serval:BIB_8921C8CAD800

Type

**Article**: article d'un périodique ou d'un magazine.

Collection

Publications

Institution

Titre

Resistively loaded antennas for ground-penetrating radar: A modeling approach

Périodique

Geophysics

ISSN-L

0016-8033

Statut éditorial

Publié

Date de publication

2005

Peer-reviewed

Oui

Volume

70

Pages

K23-K32

Langue

anglais

Résumé

The design of surface ground-penetrating radar (GPR) antennas is inherently

difficult, primarily because the presence of the air-soil interface

greatly complicates both analytic and laboratory-based approaches

aimed at characterizing the antennas. Versatile numerical simulation

techniques capable of describing the key physical principles governing

GPR antenna radiation offer new solutions to this problem. We use

a finite-difference time-domain (FDTD) solution of Maxwell's equations

in three dimensions to explore the radiation characteristics of various

bow-tie antennas (including quasi-linear antennas) operating in different

environments. The antenna panels are either modeled as having an

infinite conductivity [i.e., a perfect electrical conductor (PEC)],

a constant finite conductivity, or a Wu-King finite-conductivity

profile. Finite conductivities are accommodated through a subcell

extension of the classical FDTD approach, with the model space surrounded

by highly efficient generalized perfectly matched layer (GPML) absorbing

boundary conditions. Our results show that input impedances, radiated

waveforms, and radiation patterns of bow-tie antennas with Wu-King

conductivity profiles are largely invariant when placed in free space

or above diverse half-space earth models. By comparison, antennas

with PEC or constant finite-conductivity panels have variable characteristics

that depend somewhat on their operating environment. Quasi-linear

antenna designs tend to be less sensitive in this respect, and hence

may be suitable for a somewhat larger variety of soil conditions

than planar bow-tie antennas characterized by large flare angles.

Antennas with constant finite-conductivity panels are considerably

more robust (i.e., less sensitive to their environment) than their

PEC analogs because the loss resistance is increased, and the range

over which a significant amount of current flow occurs is decreased

when the antenna panels are resistively loaded. For the extreme case

of Wu-King conductivity profiles, the current in the antenna panels

approaches that of a quasi-infinitesimal electric dipole. This is

shown by the surface-charge distributions on the various antennas

and by the corresponding energy radiation patterns. Unfortunately,

the favorable characteristics of the latter antennas are counterbalanced

by markedly lower radiation efficiency. For the antenna designs considered

in this study, we found that the peak energy radiated into earth

models from bow-tie antennas with Wu-King conductivity profiles is

about one order of magnitude lower than for antennas with PEC terminals.

difficult, primarily because the presence of the air-soil interface

greatly complicates both analytic and laboratory-based approaches

aimed at characterizing the antennas. Versatile numerical simulation

techniques capable of describing the key physical principles governing

GPR antenna radiation offer new solutions to this problem. We use

a finite-difference time-domain (FDTD) solution of Maxwell's equations

in three dimensions to explore the radiation characteristics of various

bow-tie antennas (including quasi-linear antennas) operating in different

environments. The antenna panels are either modeled as having an

infinite conductivity [i.e., a perfect electrical conductor (PEC)],

a constant finite conductivity, or a Wu-King finite-conductivity

profile. Finite conductivities are accommodated through a subcell

extension of the classical FDTD approach, with the model space surrounded

by highly efficient generalized perfectly matched layer (GPML) absorbing

boundary conditions. Our results show that input impedances, radiated

waveforms, and radiation patterns of bow-tie antennas with Wu-King

conductivity profiles are largely invariant when placed in free space

or above diverse half-space earth models. By comparison, antennas

with PEC or constant finite-conductivity panels have variable characteristics

that depend somewhat on their operating environment. Quasi-linear

antenna designs tend to be less sensitive in this respect, and hence

may be suitable for a somewhat larger variety of soil conditions

than planar bow-tie antennas characterized by large flare angles.

Antennas with constant finite-conductivity panels are considerably

more robust (i.e., less sensitive to their environment) than their

PEC analogs because the loss resistance is increased, and the range

over which a significant amount of current flow occurs is decreased

when the antenna panels are resistively loaded. For the extreme case

of Wu-King conductivity profiles, the current in the antenna panels

approaches that of a quasi-infinitesimal electric dipole. This is

shown by the surface-charge distributions on the various antennas

and by the corresponding energy radiation patterns. Unfortunately,

the favorable characteristics of the latter antennas are counterbalanced

by markedly lower radiation efficiency. For the antenna designs considered

in this study, we found that the peak energy radiated into earth

models from bow-tie antennas with Wu-King conductivity profiles is

about one order of magnitude lower than for antennas with PEC terminals.

Création de la notice

25/11/2013 19:27

Dernière modification de la notice

20/08/2019 15:48