A new method is proposed for realizing radar illusion of an electromagnetic target by using active devices. The devices are installed around the target but may closely cover the target or not, leading to closed or open configurations. The amplitudes and phases of the active devices are determined by using T-matrix method. The numerical computation is calculated using MATLAB, and the results show that this method is convenient, flexible, and efficient, which has important significances for implementation of novel electromagnetic devices. 1. Introduction Since invisible cloaking using metamaterials was theoretically proposed and experimentally demonstrated in 2006 [1, 2], various methods have been put forward for realizing this fabulous electromagnetic (EM) phenomenon [1–8]. Generally speaking, EM invisibility, or illusion in general, can be roughly divided into four categories: (1) rendering the object transparent or invisible by controlling the parameters of metamaterials based on the scattering cancellation theory [7, 9]; (2) making the object invisible or illusory by exploiting the abnormal EM properties and the special ability to control EM waves of metamaterials based on the transformation optics theory [10, 11]; (3) invisibility using anomalous localized resonance method [12, 13]; (4) realizing invisibility or illusion using the surface integral equation of the EM field based on active devices [14–18]. So far, realization of radar illusion for an EM target is mainly based on the method of transformation optics [19–26]. Compared with the transformation optics method, active devices can be designed to work at a broadband of frequencies and do not need materials with extreme parameters. However, only a few works on radar illusion have been reported for an object by using active devices [17, 18], to the best of our knowledge. In this paper, we use two kinds of active devices to realize the radar illusion of an object. One is called the closed configuration, where the active devices are set around and closely wrap the object. The other is called open configuration, where the active devices are deployed around the object but do not cover it. The drawback of the former one is that signals from outside have been blocked, leading to poor communication for the target, while the latter does not affect the information transmission. Compared to the previous works [14–18], our scheme can not only make an object invisible to the outsider but also mimic a totally different object at a different place. It is thus a direct extension of the original work. In the next
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