The Finite-Conducting Ground’s Effect on the Inductance of a Rectangular Loop

Abstract

In an airborne electromagnetic system, which transmits time-domain half-sine current waves generated by a resonance circuit, the inductance of the transmitting loop is of great significance and directly related to parameters of the half-sine current waveform. However, in general, the effect of a finite-conducting ground on the inductance of the transmitting loop was neglected, or the ground was handled as a perfect conductor. In other words, there was no accurate method to evaluate ground’s effect on the inductance of the transmitting loop. Therefore, a new and convenient algorithm, calculating ground’s effect on the inductance of a rectangular loop, is proposed in this paper. An experiment was constructed afield, showing that the inductance increased gradually when the loop was lifted up from 0 m to 30 m, which supported the algorithm positively.

Analysis of formulas to calculate the AC inductance of different configurations of nonmagnetic circular conductors

“…As shown in Table II, FEM results are more accurate than those obtained with analytical formulas since they also have into account the change in inductance due to the skin effect. It should be highlighted that results provided by (13) and 14are independent of the conductor length.…”

“…Unfortunately, due to the mathematical complexity involved, analytical formulas are only available for the simplest geometries [11], a limited range of conductors' dimensions and a restricted interval of frequencies since they often assume a constant current density across the conductor's cross section [12]. Most of the analyzed formulas assume that the conductors are placed in a homogenous medium and therefore they do not take into account other effects such as the influence of a conducting ground plane [13] or the proximity due to the presence of nearby conductors, otherwise inductance calculations would be more complex. Depending on the distance between the conducting ground and the analyzed conductors, system inductance [14] can be substantially reduced since according to the image theory, the ground effect may be modeled by equivalent conductors placed underneath the ground, through which flow a current in opposition to that of the source.…”

Computational study on influence of RF shielding box on inductance of coil

“…Although the inductance of an inductor coil is influenced and can change, RF engineers have estimated an ideal coil inductance measured in open space. Moreover, although the interaction between an inductor and a grounded plate (surface) has been studied [12][13][14][15], directly applying these results to the RF engineering is difficult because in an RF matching box, various interactions such as the capacitive and inductive coupling simultaneously occur, and it is hard to estimate strengths of these interactions, especially in experiment. Consequentially, it is necessary to understand and evaluate the influence of the interaction on the coil inductance.…”