An Investigation of Magnetic Antennas for Ground Penetrating Radar

Abstract

Abstract-For ground penetrating radar (GPR), smaller antennas would provide considerable practical advantages. Some of which are: portability; ease of use; and higher spatial sampling. A theoretical comparison of the fundamental limits of a small electric field antenna and a small magnetic field antenna shows that the minimum Q constraints are identical. Furthermore, it is shown that only the small magnetic loop antenna can be constructed to approach, arbitrarily closely, the fundamental minimum Q limit. This is achieved with the addition of a high permeability material which reduces energy stored in the magnetic fields. This is of special interest to some GPR applications. For example, applications requiring synthetic aperture data collection would benefit from the increased spatial sampling offered by electrically smaller antennas. Low frequency applications may also benefit, in terms of reduced antenna dimensions, by the use of electrically small antennas. Under these circumstances, a magnetic type antenna should be considered in preference to the typical electric field antenna. Numerical modeling data supports this assertion.

Electrically-small TE<inf>01</inf> mode spherical wire antennas employing lossy magneto-dielectric materials

“…It has also been noted previously that the insertion of high permeability magnetic material into a loop antenna (the TE 01 spherical wire antenna is a generalized loop antenna) tends to reduce the stored magnetic energy [1,[4][5][6] and electrically-small loop antennas with magnetic cores have been studied extensively [7][8][9]. However, in [10], it is shown that the internal stored magnetic energy in a spherical wire TE 01 mode antenna by a magnetic core can be reduced only to a certain extent-as the real permeability of the lossless core material is increased, the interior of the sphere resonates causing the stored energy to increase greatly.…”

A review of selected ground penetrating radar applications to mineral resource evaluations

“…Whilst novel electrically large antennas such as magnetic (Bellett and Leat, 2003) and Vivaldi designs have been discussed in literature, the lowest frequency commercially available shielded, broadside-oriented radar antennas are centred at 100 MHz. However, most mineral exploration applications require antenna centre frequencies in the range of 20-50 MHz.…”

An Ultra-Wideband Quasi-Planar Antenna With Enhanced Gain

“…UWB antennas are required for UWB communication, impulse radio, emerging consumer electronic products, microwave imaging, non-destructive detection and ground-penetrating radar (GPR) [1][2][3][4]. Compared to narrowband systems, the UWB systems offer potentially higher image resolution and better target characterization.…”