This study focuses on the effect of different dielectric properties in the design of 3-dB planar branch line coupler (BLC) using RT5880, RO4350, TMM4 and RT6010, particularly at high frequency of 26 GHz, the fifth generation (5G) operating frequency. The analysis conducted in this study is based on the dielectric constant, loss tangent and quality factor (Q-factor) associated with the dielectric properties of the substrate materials. Accordingly, the substrate that displayed the best performance for high frequency application had the lowest dielectric constant, lowest loss tangent and highest Q-factor (i.e., RT5880), and it was chosen to enhance our proposed 3-dB BLC. This enhanced 3-dB BLC was designed with the inclusion of microstrip-slot stub impedance at each port for bandwidth enhancement, and the proposed prototype had dimensions of 29.9 mm × 19.9 mm. The design and analysis of the proposed 3-dB BLC were accomplished by employing CST Microwave Studio. The performance of scattering parameters and the phase difference of the proposed BLC were then assessed and verified through laboratory measurement.

本研究的重点是不同介电特性在使用 RT5880、RO4350、TMM4 和 RT6010 的 3-dB 平面支线耦合器 (BLC) 设计中的影响，特别是在 26 GHz 的高频，即第五代 (5G) 工作频率下。本研究中进行的分析基于与基板材料的介电特性相关的介电常数、损耗角正切和品质因数（Q 因数）。因此，在高频应用中表现出最佳性能的基板具有最低的介电常数、最低的损耗角正切和最高的 Q 因数（即 RT5880），因此选择它来增强我们提出的 3-dB BLC。这种增强型 3-dB BLC 的设计在每个端口都包含微带槽短截线阻抗以增强带宽，并且提议的原型尺寸为 29。9 毫米 × 19.9 毫米。建议的 3-dB BLC 的设计和分析是通过使用 CST Microwave Studio 完成的。然后通过实验室测量评估和验证散射参数的性能和所提出的 BLC 的相位差。