In this paper, a compact broadband 4 × 4 Butler matrix (BM) as a feeding network for antenna array is presented and studied. The broadband performance of the BM occurs when it operates in the almost equal difference of phases and coupling throughout the operating band. The different components of the proposed design such as branch-line coupler, crossover, and Schiffman line phase shifter are designed and optimized to be low loss and wideband. The total size of the BM is 37 mm × 47 mm, equal to 0.64λ₀ × 0.81λ₀ in design frequency at 5.2 GHz. The measurement bandwidth for fabricated structure on the FR4 substrate is 24 % achieved from return loss lower than −10 dB. The beam directions are measured at −15, −43.2, +43, and +15° at 5.2 GHz for each input port 1–4 excitation respectively with the gain value of 10.2 ± 0.2 dB and sidelobe levels of −8.2 ± 1.2 dB. The Final BM exposures phase errors of 3 ± 1.7° with the amplitude imbalance of less than ±1 dB over the operational band.

在本文中，提出并研究了一个紧凑的宽带 4 × 4 巴特勒矩阵 (BM) 作为天线阵列的馈电网络。当 BM 以几乎相等的相位差和整个工作频带的耦合工作时，就会出现宽带性能。所提议设计的不同组件，例如支线耦合器、分频器和希夫曼线移相器，都经过设计和优化，以实现低损耗和宽带。BM 的总尺寸为 37 mm × 47 mm，等于 0.64λ ₀  × 0.81λ ₀设计频率为 5.2 GHz。FR4 基板上装配结构的测量带宽是从低于 -10 dB 的回波损耗实现的 24%。对于每个输入端口 1–4 激励，波束方向分别在 5.2 GHz 的 -15、-43.2、+43 和 +15° 处测量，增益值为 10.2 ± 0.2 dB，旁瓣电平为 -8.2 ± 1.2 dB。最终 BM 在操作频带内暴露 3 ± 1.7° 的相位误差，幅度不平衡小于 ±1 dB。