Ultra-wide band (UWB) pulse radars have an immeasurable potential for high range resolution imaging in the near field and are applicable to accurate spatial measurement for rescue robots or security systems. SAR (Synthetic Aperture Radar) algorithm can create an accurate and stable target image in the near field. However, in the case of complex or multiple targets, this algorithm suffers from increased shadow regions or a false image caused by multiple scattering echoes. In general, a propagation path of a multiple scattering wave is different from that of a single scattering one, then a multiple scattering echo includes an independent information of target surfaces. This paper proposes a shadow region imaging algorithm based on the aperture synthesis for multiple scattering data. The performance evaluations in numerical simulation reveal that the proposed method remarkably enlarges the visible range of target surfaces without a priori information of surrounding environment.%UWB （超広帯域）レーダは高い距離分解能を有し，各種工業製品の非接触精密計測，救助用ロボット及びセキュリティシステム等の近距離空間計測に適する．地表面計測等で利用される合成開口レーダは精度・安定性に優れ，近距離画像化技術としても有用である．一方，多数の凹凸面を有する複雑目標または複数目標の場合，同手法では影領域の増大及び多重散乱波による虚像が問題となる．一般に多重散乱波は単散乱波と異なる位相停留経路を通過し，単散乱波とは独立な目標境界の位置情報を保有する．本稿では二重散乱波を合成開口処理に適用することで，直接的な影領域画像化手法を提案する．提案手法は周囲環境の先見情報を必要とせず，且つ従来の画像化範囲を飛躍的に拡大することを数値計算により示す．
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