Shape reconstruction methods are particularly well suited for imaging of concealed targets. Yet, these methods are rarely employed in real nondestructive testing applications, since they generally require the electrical parameters of outer object as a priori knowledge. In this regard, we propose an approach to relieve two well known shape reconstruction algorithms, which are the linear sampling and the factorization methods, from the requirement of the a priori knowledge on electrical parameters of the surrounding medium. The idea behind this paper is that if a measurement of the reference medium (a medium which can approximate the material, except the inclusion) can be supplied to these methods, reconstructions with very high qualities can be obtained even when there is no information about the electrical parameters of the surrounding medium. Taking the advantage of this idea, we consider that it is possible to use shape reconstruction methods in buried object detection. To this end, we perform several experiments inside an anechoic chamber to verify the approach against real measurements. Accuracy and stability of the obtained results show that both the linear sampling and the factorization methods can be quite useful for various buried obstacle imaging problems.
In this study, the authors present a novel dipole antenna for microwave imaging (MWI) applications. Different from the previous works, the designed dipole is compact while having a wide‐impedance bandwidth of 1–4.2 GHz along with a moderate gain. In particular, the largest dimension of the antenna is 6 cm, which is 0.2 wavelength at the very lower end of the operating frequency bandwidth. Furthermore, the resultant design has a cross‐polarisation level <20 dB. Important characteristics of the proposed design are given with the simulations through analysis system high‐frequency structure simulator. Obtained simulation results are also shown to be consistent with the measurements. In addition to measuring fundamental parameters of the designed dipole, they also test the proposed antenna in a circular MWI system. In this context, several dielectric scatterers are measured in a circular scanner and obtained scattered field measurements are supplied to the well‐known contrast source inversion method. Imaging results show that the proposed antenna is quite suitable for MWI applications.
Within the past decade, once limited biomedical application of microwave imaging started to expand from the breast cancer imaging to imaging of other anomalies. One such anomaly is the brain stroke where the application of microwave imaging is two folds. One application is the identifying the source of stroke that is to categorize whether the stroke stems from blockage (ischemic) or bleeding (hemorrhagic). The other possible application is the continuous imaging of the progression of hemorrhagic stroke during the post-acute stage. In this work, a phantom for emulating the dielectric properties of the lossy brain tissue is given for testing of the microwave devices for continuous monitoring. The recipe is simple and is composed by mixing carboxymethyl cellulose, ethylene glycol, and deionized water. The recipe is simple, has viscose texture, and can be easily composed. Dielectric property measurements and comparison with the literature data is given in this paper.
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