A novel ultrawideband (UWB) antenna, called the Shark antenna, and designed especially for transient applications is proposed in this paper. A Shark antenna array is also conceived in order to obtain a high power UWB pulse radiation source through the frequency band [800 MHz-8 GHz]. For this application, the elementary antenna must be compact, non-dispersive, and the array must have a high transient front to back ratio. The geometry of the Shark antenna and its radiation characteristics are detailed. Moreover, an approach which evaluates the transient front to back ratio of a square array is presented. Index Terms-High power radiations, miniature ultrawideband (UWB) antenna, transient array.

The conception of a novel Ultra-Wideband (UWB) antenna array, designed especially for transient radar applications through the frequency band (300 MHz–3 GHz), is proposed in this paper. For these applications, the elementary antenna must be compact and nondispersive, and the array must be able to steer in two dimensions. The geometry of the elementary antenna and its radiation characteristics are presented. The array beam steering is analyzed and a technique making the increase of the transient front-to-back ratio possible is described.

Abstract-An innovative radar imaging system, based on the capability of a fixed UWB array to radiate short pulses in different directions along time with the principle of electronic beam steering, is presented in this paper. To demonstrate its concept, the analysis presented in this paper is based on simulation results. As function of the use of either only one antenna or several antennas in reception, two radar imaging algorithms have been developed and are detailed in this paper. These algorithms permit to obtain an image of the analyzed scene thanks to the transient beam pattern of the array used in emission. Finally, with a same analyzed scene, these algorithms have been compared with the time reversal method and the back projection algorithm, in association with a SAR imaging system. The conditions of applicability of these methods are also discussed.

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