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A geophysical exploration employing ground‐penetrating radar (GPR) and electrical resistivity tomography (ERT) was conducted at the Western Cemetery, Giza, Egypt, in 2021–23 by a joint research team of Higashi Nippon International University, Tohoku University and the National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Egypt. We believe we found an anomaly: a combination of a shallow structure connected to a deeper structure. The shallow structure, which is L‐shaped in the horizontal plane, 10 m by 10 m, was clearly imaged by GPR. It seems to have been filled with sand, which means it was backfilled after it was constructed. It may have been an entrance to the deeper structure. Its depth is of up to 2 m, measured from the ground surface. Below this structure, ERT reveals a highly electrically resistive anomaly, which extends over an area of about 10 m by 10 m. The depth of the structure is about 5–10 m below the surface. Electrically resistive material in a sand dune can be a mixture of sand and gravel, including sparse spacing or air voids within it. Neither GPR nor ERT could identify the properties of the anomaly. [ABSTRACT FROM AUTHOR]

Crosshole borehole radar measurement is needed to compensate the antenna transfer functions in polarimetric single-hole radar measurement with combinations of a dipole antenna and a cylindrical conducting slot antenna. This paper presents a method to estimate the antenna transfer functions from the single-hole measurement alone. A small dipole model in a homogeneous medium is used to approximate the relationship between the direct coupling wave in the single-hole measurement and the direct wave in crosshole measurement (antenna transfer function). We show that the far field crosshole signal approximately has the same frequency dependency as the time derivative of the direct coupling signal measured via single-hole measurement. We experimentally demonstrate that the measured far field waveforms have good agreement with the time derivative of the measured direct coupling waveform for dipole–dipole and slot–slot arrangements with an antenna separation of 1.6 m. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(11): 11–21, 2000 [ABSTRACT FROM AUTHOR]

A borehole radar is one form of ground penetrating radar which can be used in deep boreholes. We have been developing a directional borehole radar system with a conformal array antenna on a conducting cylinder. In this paper, we propose a 2-D MUSIC algorithm for the circular array of a directional borehole radar, which can be used to estimate the 2-D source location in a plane containing the array. A decorrelation technique is employed and we derive an algorithm which can determine the locations of two coherent sources. Experimental results obtained with the borehole radar show that this algorithm can accurately estimate parameters with a circular array having a radius of 0.03 m, which is much less than the signal wavelength of 0.8 m. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80(6): 69–77, 1997 [ABSTRACT FROM AUTHOR]

Unwanted electromagnetic waves radiated from equipment making use of electromagnetic energy create numerous societal problems. The prevention of these problems has been studied extensively. In this paper, a method for estimating the location of the unwanted electromagnetic waves is studied. Since it is difficult to make the antenna aperture large especially at low frequencies, a search for electromagnetic wave source via a synthetic aperture technique is proposed. In the estimated electromagnetic source distribution by this method, images similar to the antenna sidelobes appear. It is demonstrated by computer simulation that the images can be suppressed by use of the synthetic aperture method with subarrays or use of Mill's cross method. Discrepancies between the true source location and the estimated location have been found in regard to the synthetic aperture length and the geometrical relationship with respect to the aperture center. It has been found that the antenna configuration with the synthetic aperture length of 10 λ can estimate an electromagnetic wave source within 10 λ square with accuracy of less than 1/4 λ square. Therefore this method is sufficiently practical if the location of the source is restricted somewhat. [ABSTRACT FROM AUTHOR]

SUMMARY Damages on the surfaces of concrete buildings can easily be detected by visual inspection and can be repaired. However, damages inside walls need nondestructive inspection techniques to be detected, located, and identified. There has been a great demand for such techniques particularly after the 3.11 Great East Japan Earthquake. Ground-based synthetic aperture radar (GB-SAR) is a technique that can be potentially used for inspection of concrete walls in a nondestructive and noncontacting manner. The paper reports a fundamental experiment with a polarimetric GB-SAR system to detect internal damage in a concrete specimen caused by horizontal loading simulating earthquakes. The results show that the system does not have enough resolution to visualize individual defects, and that the effect of steel rebars installed inside the concrete is so strong that it masks weak responses. However, polarimetric analysis demonstrated the capability to minimize the effect of rebars by rearranging polarization basis and to extract weak responses. In particular, internal damages could be detected by observing the volume scattering component in this experiment. [ABSTRACT FROM AUTHOR]

It has been brought to the attention of the publisher that an error appeared in the citation of the original Japanese publication of the above article. It should read as follows: Translated from Denshi Joho Tsushin Gakkai Ronbunshi Vol. 79-B-II. No. 9, September 1996, pp. 574–582. We apologize for any inconvenience this may have caused the authors. [ABSTRACT FROM AUTHOR]

There have recently been analyses of lightning electromagnetic fields using the FDTD method. However, large-scale three-dimensional analyses of a real environment have not been considered, because the FDTD method has a huge computational cost in large-scale analysis. Thus, we have proposed a three-dimensional moving window FDTD (MW-FDTD) method with parallel computation. Our method has a lower computational cost than the conventional FDTD method and the original MW-FDTD method. In this paper, we study the computational performance of MW-FDTD parallel computation and large-scale three-dimensional analysis of lightning electromagnetic fields on a real terrain model using our MW-FDTD with parallel computation. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(2): 20-27, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22368 [ABSTRACT FROM AUTHOR]

SUMMARY Analysis of lightning electromagnetic field using the finite-difference time-domain (FDTD) method has been studies in recent year. However, large-scale analysis on real environment has not been considered, because the FDTD method requires huge computational cost on large-scale analysis. We proposed a three-dimensional moving window FDTD (MW-FDTD) with parallel computation and applied to large-scale analysis of lightning electromagnetic field with a real numerical terrain model. In this paper, we have studied about large-scale analysis of lightning electromagnetic field with real urban models considering many buildings using our MW-FDTD with parallel computation. We have shown effects of observed electromagnetic field on urban model. [ABSTRACT FROM AUTHOR]