A low‐profile wideband planar phased array, working in X band and with two‐dimensional (2‐D) beam scanning characteristic is presented. In order to meet the requirements of wideband 2‐D beam scanning and low‐profile performance, a cavity‐backed slot stacked microstrip element is introduced. The array element is mainly composed of the open‐ended microstrip line printed on the bottom substrate, which backed by a rectangular metal cavity, and dual layer patches etched on the middle substrate and the top substrate, respectively. A vertical transition structure is used to feed the microstrip line and connect the active T/R module, which is similar to the coaxial probe. The thickness of the proposed element is only 4.5 mm (0.12 λ_L, λ_L is the wavelength of the lowest frequency). Based on the simulated design, an 8 × 8 planar phased array prototype has been fabricated and measured. The experimental results show that the proposed array have achieved the maximum scanning angle of ±45° in the H‐plane and ± 30° in the E‐plane across the frequency range of 8 ~ 12 GHz. Therefore, the proposed array can be used as a sub‐array of larger low‐profile wideband phased arrays for 2‐D beam scanning applications, and also validate the introduced design concept.

中文翻译：

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背腔狭缝微带元件的低轮廓宽带平面相控阵列，用于二维束扫描应用

提出了一种低剖面宽带平面相控阵，其工作于X波段并且具有二维（2-D）光束扫描特性。为了满足宽带二维光束扫描和低剖面性能的要求，引入了背腔槽堆叠微带元件。阵列元件主要由印刷在底部基板上的开放式微带线（由矩形金属腔支持）和分别在中间基板和顶部基板上刻蚀的双层贴片组成。垂直过渡结构用于馈送微带线并连接有源T / R模块，类似于同轴探头。所提出的元件的厚度是只有4.5毫米（0.12  λ_大号，λ_大号是最低频率的波长）。基于仿真设计，已经制造并测量了一个8×8平面相控阵原型。实验结果表明，所提出的阵列在8〜12 GHz的频率范围内在H平面中的最大扫描角度为±45°，在E平面中的最大扫描角度为±30° 。因此，所提出的阵列可以用作二维波束扫描应用中较大的低剖面宽带相控阵的子阵列，并且可以验证引入的设计概念。