Underground Anomaly Detection by Electromagnetic Shock Waves

Abstract

A method for the detection of underground anomalies by electromagnetic (EM) shock waves is presented. Following Grischkowsky et al. [Phys. Rev. Lett., vol. 59, pp. 1663-1666, 1987, an EM shock wave will develop in a dielectric medium by exciting a pulse which leaks into the dielectric bulk from a transmission line. A shock wave occurs when the group velocity in the line exceeds the phase velocity in the dielectric. This mechanism is similar to Cherenkov radiation. In this paper the transmission and reception of the EM shock wave between two identical leaky transmission lines is introduced. For underground detection, the two lines are placed in boreholes and are made in a manner in which the speed of propagation in the line is faster than the speed of propagation in the ground. The effect on the shock wave by an underground anomaly such as a dielectric or metallic pipeline located between the two boreholes is studied. The anomaly scatters the shock wave, resulting in a detectable disturbance in the received signal. The time delay of this disturbance, with respect to the time when the pulse was transmitted, is correlated with the location of the object. Numerical examples are presented by using a two-dimensional finite-difference time-domain algorithm.

Wave Propagation Between Buried Antennas

“…The antenna dielectric layer was set to . A transverse-EM bipolar Gaussian pulse was injected at the input port [11], [12] (1a)…”

A Deep Learning-Based Electromagnetic Signal for Earthquake Magnitude Prediction

“…In this way, the sensitivity of the sensor can be greatly improved. In addition, a magnetic negative feedback technology is proposed, which breaks through the limitation of the resonance frequency point, broadens the bandwidth of the sensor monitoring signal, and solves the phenomenon of phase mutation in the frequency band [ 21 ]. Then, a CNN model is proposed to classify the earthquake magnitude according to the data of the inductive electromagnetic sensor.…”

6‐kV, 130‐ps rise‐time pulsed‐power circuit featuring cascaded compression by fast recovery and avalanche diodes

“…Nanosecond and sub‐nanosecond pulses having high peak power combined with high‐speed bursts can be used in applications such as: through‐wall imaging [1]; underground detection [2], biological research [3]; and in high energy density physics experiments. Although technologies such as spark‐gaps [4] and pulse compression by non‐linear transmission lines (NLTLs) [5] can reach tens to hundreds of kilo‐volts in the sub‐nanosecond regime, the pulse repetition frequency (PRF) of these technologies is limited to the sub‐kilohertz range.…”