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Petroleum Geo-Electrical Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
A rock of greater electrical resistivity favors more propagation of radar waves into the ground, and also low-frequency radar waves achieve greater depth. A more conductive rock and high frequency are limited to a lower depth. Additionally depth determination is also related to the geometrical arrangement of the transmitter/receiver antennas at the surface. For shallower penetration determination, transmitters and receivers are placed on the surface along a line at a small distance. For covering a large survey area, the transmitters and receivers are moved apart on the survey line but the spread between them is kept constant. The radar waves reflected back from deeper rock (layer II) are weak, broad and lack sharpness and resolution compared to the signals from shallower rock (layer I).
GPR Principles and Applications
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
For low-frequency radar applications (10–200 MHz), manufacturers rely on resistively loaded dipoles for the transmitter and receiver antennas, as depicted in Figure 70.3. Such antennas can be unwieldy in difficult terrain, such as in forests, where cut lines up to 4 m wide are required. Alternatively, dipole antennas may be placed collinearly, allowing the radar system to be housed within a long “snake” and towed easily along a trail. The Malå Geoscience’s RTA system and the UltraGPR from Groundradar, Inc., in Vancouver, Canada (www.groundradar.com), both employ such a design with real-time radar receivers for long-range imaging of mineral deposits (Figure 70.4). Such a collinear orientation of radar antennas often produces clutter patterns on the received radar profiles due to the end fire from the antennas reflecting off of aboveground targets such as trees.
Sub-Surface Tomography Applications
Published in Blaunstein Nathan, Yakubov Vladimir, Electromagnetic and Acoustic Wave Tomography, 2018
Vladimir Yakubov, Sergey Shipilov, Andrey Klokov, Nathan Blaunstein
Moreover, passive radar is non-detectable and not degraded by path error or speckle noise. Essentially, detecting various thermic emissions from the target under MMW-radar searching provides additional information about its peculiarities compared with that obtained by low-frequency radar or optical and infrared (IR) detectors, for more accurate estimation of the target response.
Development of a logarithmic spiral antenna in UWB GPR for humanitarian demining
Published in Electromagnetics, 2018
GPR or Ground Penetrating Radar is a method for detecting buried objects that radiates an Ultrawide band (UWB) electromagnetic signal to the objects underground and detects the reflected waves (echoes). GPR design depends on the survey level and is different for the deep and shallow levels. Also, the resolution of the related application influences the operating frequency and design of the radar. Typically, low-frequency radar signals have good penetrating capability while high-frequency waves have better spatial resolution (Genderen, Nicolaescu, and Zijderveld 2003).