Microwave imaging from total electric field data

A novel gradient-based inverse scattering method for imaging inhomogeneous objects from time-domain data of only total electric field is presented. Unlike most inverse scattering methods, the proposed method does not require the explicit information of the incident field illuminating a region of interest. Numerical simulations demonstrate the effectiveness of the method.2014 IEEE Antennas and Propagation Society International Symposium, APSURSI 2014; Memphis Convention CenterMemphis; United States; 6 July 2014 through 11 July 201

Application of time reversal to imaging electrical properties of inhomogeneous cylindrical objects

A time-domain inverse scattering approach using time-reversed fields for reconstructing electrical parameters of cylindrical objects has been proposed in a previous work. The approach does not require the explicit knowledge of incident fields illuminating the object. The cost functional represented in terms of the time-reversed fields was minimized by a genetic algorithm (GA). In this paper, we propose a gradient-based minimization for reconstruction of an inhomogeneous object for which GA can not be applied due to computational complexity. The time-reversed fields are calculated by time-reversing the equivalent current sources determined by the total fields recorded on a measurement line. Numerical simulations are carried out to show the effectiveness of the proposed method.8th European Conference on Antennas and Propagation, EuCAP 2014; The Hague; Netherlands; 6 April 2014 through 11 April 201

Image reconstruction of objects with time reversal and equivalent fields

Most inversion schemes for reconstructing electrical parameter distributions of unknown objects assume the explicit knowledge of incident fields illuminating them. We have proposed an inversion approach based on the field equivalence principle without requiring the knowledge of incident fields. The approach, however, requires measurement of both electric and magnetic tangential components of total field on the observation surface. In this paper, a new inversion scheme for the reconstruction from measured data of only electric tangential components is presented using time reversal and equivalent fields. Numerical reconstruction examples show the validity of the proposed scheme.2013 15th International Conference on Electromagnetics in Advanced Applications, ICEAA 2013; Turin; Italy; 9 September 2013 through 13 September 201

Iterative multiscaling strategy incorporated into time domain inverse scattering method for cross-borehole imaging

We consider cross-borehole imaging of buried objects embedded in a large search area by using a time domain inverse analysis. For simplicity, a two-dimensional model is examined. In order to avoid trap into false solution and enhance the achievable spatial resolution, the iterative multiscaling strategy combined with the forward-backward time-stepping method is proposed. Preliminary results show the effectiveness of proposed method.IGARSS 2011 - 2011 IEEE International Geoscience and Remote Sensing Symposium : Vancouver, BC, Canada, 2011.07.24-2011.07.2

Two-dimensional Forward-Backward Time-Stepping approach for tumor detection in dispersive breast tissues

The Forward-Backward Time-Stepping (FBTS) technique is applied to determine the presence and location of malignant tumor in the heterogeneous breast model. A new strategy is integrated in the FBTS algorithm to accurately estimate the dielectric properties of tissues. We demonstrate 2-D FBTS technique utilizing the numerical dispersive breast model in a free space. This new strategy manipulating Debye dispersion equation is proposed to treat dispersive case. Numerical simulation results show the FBTS algorithm has the potential to provide useful quantitative information of the breast\u27s internal composition.2009 Mediterranean Microwave Symposium (MMS) : Tangiers, Morocco, 2009.11.15-2009.11.1

Microwave breast imaging by the filtered forward-backward time-stepping method

In this paper, an inverse scattering technique referred to as the filtered forward-backward time-stepping method is applied to microwave imaging for breast cancer detection. A two-dimensional numerical breast phantom (derived from MR images) with high contrast between fat and fibroglandular tissues, and low contrast between fibroglandular and tumor tissues are used to assess the efficacy of the proposed method.2010 URSI International Symposium on Electromagnetic Theory (EMTS 2010) : Berlin, Germany, 2010.08.16-2010.08.1

マイクロ波CTマンモグラフィの開発

24個の固定ダイポールアンテナを用いて三次元マイクロ波CT実験を行い，スーパーコンピュータを用いてForward-Backward Time Stepping（FBTS）法によるCT計算を行った．その結果得られた知見は，FBTS法が雑音に強いこと，及び計算の初期設定やキャリブレーション設定が精度向上に重要なことである．また計算モデル化が容易な広帯域平面アンテナの開発も行った．これらの知見を生かし，FBTS法マイクロ波CTマンモグラフィ装置の概念設計を行った