HPEM Subsurface Cavity Detection via Electromagnetic Pulse Excitation
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Solution Overview
Problem
Current methods for detecting subsurface cavities and materials, such as metal detectors and ground penetration radar, have limited penetration depth and effectiveness in locating irregularities in soil or rock layers, making it difficult to detect tunnels and cavities deep in the ground.
Innovation Solution
A method utilizing a high-power-electromagnetics (HPEM) radiation source that emits electromagnetic pulses to excite electromagnetically reactive structures in the subsurface, generating a transillumination signal through which cavities and tunnels can be detected by analyzing the response signals, allowing for deeper penetration and improved spatial and time resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If traditional metal detectors or ground penetration radar are used, then the detection method is simple and well-established, but the penetration depth is limited to a few metres or centimetre range
Solution Approach 1:
The patent changes the fundamental parameters of the detection system by using HPEM pulses with peak power in the range of 1 MW to 1 GW and pulse durations of 1 ns to 100 ns, operating in the frequency range of 1 MHz to 10 GHz. These parameter changes enable penetration depths of several tens of metres while maintaining detection capability through the excitation of electromagnetically reactive structures.
2Length of stationary object
If HPEM radiation source with high power is used, then penetration depth increases to several tens of metres, but the device complexity increases
Solution Approach 1:
The patent employs periodic pulsed action with pulse durations of 1 ns to 100 ns and repetition frequencies that allow the subsurface structures to return to their ground state between pulses. This periodic excitation enables deep penetration while managing system complexity through controlled, intermittent operation rather than continuous high-power emission.
Solution Approach 2:
The patent uses electromagnetically reactive structures (such as conductive objects, metallic layers, or cavities) as intermediaries that convert the HPEM pulse energy into detectable response signals. These intermediaries enable the detection system to achieve deep penetration without requiring the receiver itself to have extremely high sensitivity, thus managing system complexity.
3Loss of time
If short pulse duration is used, then time resolution improves, but the energy per pulse decreases
Solution Approach 1:
The patent uses very short pulse durations of 1 ns to 100 ns that rush through the subsurface before significant energy dissipation can occur. This allows the system to achieve excellent time resolution for locating deep structures while the high peak power (1 MW to 1 GW) compensates for the low energy per pulse through the intensity of the brief excitation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the detection and localization of tunnels and cavities at greater depths than traditional methods, with enhanced sensitivity and spatial resolution, using powerful electromagnetic pulses that excite conductive structures to emit characteristic response signals.
Implementation Method 1
a high-power-electro-magnetics (HPEM) radiation source radiates at least one electromagnetic pulse into the section. The pulse is used to excite possible electromagnetically reactive structures present in the section. As a result of the pulse impinging on such a structure, the latter is excited to emit an electromagnetic response signal.
Data Source
AI summary
In a method for generating a transillumination signal of a section of the subsurface, an HPEM radiation source radiates an electromagnetic pulse into the section for the purpose of exciting electromagnetically reactive structures to emit an electromagnetic response signal. For the pulse, a pulse duration of at most 500 ns, a center frequency in the range between 10 MHz and 10 GHz, and a bandwidth in the range from 10% to 150% of the center frequency is set. The transillumination signal is formed as the sum of response signals received at a measuring location. In a method for detecting a cavity in the subsurface, the above method is carried out, and the structures are detected from the transillumination signal with the aid of a detection method, and the cavity is detected if the structures satisfy a detection criterion.