This article presents a new kind of finline in double-layer dielectric substrate and its beamforming circuit of Butler matrix in the millimeter-wave band. The finline is constructed by inserting a slotline between two dielectric substrate layers. In this configuration, it is bounded within a closed structure composed of a double-layer dielectric substrate and two rows of via-hole arrangement, contributing to low dispersion and low radiation loss of the finline characteristics. The proposed finline design aims to provide a low-complexity and low-loss transmission line which is applied to the Butler matrix design. A $4\times 4$ Butler matrix for 4 switchable beams is realized by using the finline in the double-layer dielectric substrate. In addition, a waveguide-to-finline transition is developed as a feeding circuit for the Butler matrix. Characteristics of the proposed transition and the Butler matrix were analyzed by electromagnetic analysis of the finite element method and demonstrated by experiments at 79 GHz. The proposed Butler matrix obtains a wideband characteristic and an acceptable insertion loss of 2.42 dB. The array factor which is calculated from the measured amplitude and phase outputs 4 switchable beams with the beam directions of +14°, −46.5°, +46.5° and −14°, respectively. The proposed beamforming circuit using finline in double-layer dielectric substrate would be attractive for millimeter-wave applications due to its performance and low cost.

中文翻译：

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双层介质衬底中使用Finline的毫米波巴特勒矩阵波束形成电路

本文提出了一种新型的双层电介质鳍片及其在毫米波段巴特勒矩阵的波束形成电路。通过在两个介电基板层之间插入缝隙线来构造鳍线。在这种配置中，其被限制在由双层电介质基板和两排通孔布置组成的封闭结构内，从而有助于降低鳍线特性的色散和辐射损耗。所提出的鳍线设计旨在提供一种低复杂度和低损耗的传输线，该传输线应用于巴特勒矩阵设计。一种 4美元/次4美元 通过在双层电介质基板中使用鳍线来实现4条可切换光束的巴特勒矩阵。另外，开发了波导到最终的过渡，作为巴特勒矩阵的馈电电路。拟议的过渡和巴特勒矩阵的特征通过有限元方法的电磁分析进行了分析，并通过79 GHz的实验进行了证明。提出的巴特勒矩阵获得了宽带特性，可接受的插入损耗为2.42 dB。根据测得的振幅和相位计算出的阵列系数输出4个可切换光束，光束方向分别为+ 14°，-46.5°，+ 46.5°和-14°。所提出的在双层电介质衬底中使用鳍线的波束形成电路由于其性能和低成本而对于毫米波应用将具有吸引力。