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Research on application of ground penetrating radar array method based on plane beam signal in diferent geological models

Cui Fan, Chen Yi, Zhang Yongqi, Du Yunfei

Acta Geophysica

2021

Vol. 69, no. 6

2241--2260

The traditional common-offset ground penetrating radar method measures point by point along the survey line with a single transmitter and a single receiver. Due to the influence of the antenna radiation power and the low-pass filtering function of the earth medium, an intense amplitude gain cannot be obtained when the signal is intercepted. This article addresses a plane beam signal ground penetrating radar array observation method based on high radiation power gain. The transmitting antenna array simultaneously excites the pulse signal with the same center frequency. All the transmitted signals interfere with each other at the near surface to form a plane beam signal, and the electromagnetic energy is superimposed mutually to increase the radiation power. We applied the plane beam signal ground penetrating radar array method to different geological models constructed by the finite difference time-domain (FDTD) algorithm for numerical simulation in this research. Since there are various offsets in the array ground penetrating radar observation method, we introduce a composite frequency shift-perfect matching layer (CFS-PML) based on the recursive convolution method as the absorbing boundary condition. It eliminates the problem of secondary refection caused by the angle variation of the incident wave. The research result shows that the plane beam signal illuminates the target uniformly in space, can eliminate the discontinuity in profile data caused by the directivity of the antenna, improve the stability and quality of the echo signal, and enrich the target response parameters.

Metody wyznaczania składowej dyspersyjnej w analizie propagacji szerokopasmowych impulsów elektromagnetycznych

Butryło B.

Pomiary Automatyka Kontrola

2010

R. 56, nr 2

119-121

W artykule przedstawiono metodę analizy pól elektromagnetycznych w układach zawierających materiały dyspersyjne. Rozpatrzono wpływ zmiany rzędu wielomianu aproksymującego zmiany pola oraz wielkości kroku całkowania numerycznego na precyzję i stabilność szerokopasmowego algorytmu metody elementów skończonych.

The paper deals with broadband formulation of the finite element time domain (FETD) method. The presented version of the FETD algorithm is based on the second order wave equation. The dispersive properties of materials are taken into account by step-by-step, recursive evaluation of the convolution integral. The resonance absorption of the analyzed materials is described by a linear combination of the complex Lorentz kernels shifted in the frequency domain. The presented, unified formulation of the recursive convolution scheme is based on the local, polynomial approximation of the electromagnetic waveform. A validation example for the algorithm is provided for a generic semi-cylinder component made of nondispersive material. It is coated by a thin layer dispersive, narrowband dielectric. The accuracy and computational cost of the presented multi-step algorithm are examined. The transient state simulation results depend on the approximation scheme order and the assumed time step size.