The frequency diverse array (FDA) radar has been extensively studied due to its unique range-angle dependent beampattern. Time-invariant spatial patterns have been reported for FDAs proposed so far. However, some recent studies indicate that the patterns obtained by using these methodologies neglect the time-range or frequency-phase relationship, and the definition of time in some equations are misinterpreted which results in erroneous conclusions. Taking the time-variant property of FDA beampatterns into consideration, in this study, the authors propose a short range FDA radar to generate a time-variant focused range-angle dependent transmit beampattern, where chirp waveform with multi-carrier FDA architecture is used. Both the fixed and time-modulated frequency offsets are considered to analyse the proposed FDA radar. The frequency offset employed across each element is generated by chaos sequence and sine function. By compensating the propagation delays of signals, the transmitted signals sum up constructively to focus on the desired range-angle sector only at a specific instant of time. Numerical results are implemented to verify the validity of the proposed schemes.

中文翻译：

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时变聚焦雷达的时变聚焦距角相关波束方向图合成

由于其独特的与射程角相关的波束图，对频率变化阵列（FDA）雷达进行了广泛的研究。迄今为止，已经报道了针对FDA的时不变空间模式。但是，最近的一些研究表明，使用这些方法获得的模式忽略了时间范围或频率-相位关系，并且某些方程式中的时间定义被错误地解释，从而导致错误的结论。考虑到FDA波束图的时变特性，在这项研究中，作者提出了一种短程FDA雷达来生成时变聚焦范围角度相关的发射波束图，其中使用了具有多载波FDA架构的线性调频波形。固定频偏和时间调制频偏均被考虑用于分析建议的FDA雷达。跨每个元素采用的频率偏移由混沌序列和正弦函数生成。通过补偿信号的传播延迟，所传输的信号进行建设性的求和，以仅在特定时间聚焦在所需的范围角度扇区上。数值结果验证了所提方案的有效性。