This letter presents a broadband active Van Atta array system at $X$ -band, which is used for monostatic radar cross section (RCS) modulation and enhancement. The active system mainly consists of two uniform linear arrays (ULAs) and an active four-channel radio frequency (RF) amplifying circuit. By introducing the electrically modulated attenuator (EMA) into the active system, the transmission gain of the proposed four-channel RF amplifying circuit is controlled by a voltage signal from a control circuit and the backscattering field of the system can be sequentially modulated. The system’s performance of RCS modulation and retrodirectivity are validated through measurement over a relative bandwidth of 40% centered at 10 GHz. The modulation range of monostatic RCS is generally more than 20 dB at the $X$ -band. Its 3-dB retrodirective range and maximum equivalent RCS are 70°–120° and 1.4–3.9 dBsm varying from 8 to 12 GHz, respectively.

中文翻译：

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用于 X 波段单站 RCS 调制的宽带有源范阿塔阵列系统

这封信介绍了一个宽带有源 Van Atta 阵列系统，位于 $X$ -band，用于单基地雷达截面 (RCS) 调制和增强。有源系统主要由两个均匀线性阵列（ULA）和一个有源四通道射频（RF）放大电路组成。通过将电调制衰减器 (EMA) 引入有源系统，所提出的四通道射频放大电路的传输增益由来自控制电路的电压信号控制，系统的反向散射场可以顺序调制。该系统的 RCS 调制和后向性性能通过以 10 GHz 为中心的 40% 相对带宽上的测量得到验证。单站RCS的调制范围一般在20dB以上 $X$ -乐队。其 3-dB 反向范围和最大等效 RCS 分别为 70°–120° 和 1.4–3.9 dBsm，从 8 GHz 到 12 GHz 变化。