脉冲传输线的介质材料选择和参数设计对传输线的损耗具有至关重要的影响,根据分布参数理论和电磁场微波理论,给出环氧玻璃纤维FR-4和聚四氟乙烯F₄B两种材料的损耗计算公式,在微带特性阻抗为50 Ω,工作频率为10 GHz时,FR-4和F₄B的介质衰减系数分别为0.095 dB/cm和0.002 3 dB/cm;当微带厚度为18 μm,介质材料厚度为0.25 mm时,FR-4和F₄B的导体衰减系数分别为0.049 9 dB/cm和0.035 7 dB/cm.数值计算和仿真结果表明,F₄B材料传输线的介质损耗和导体损耗相对较低,是一种较好的介质材料,选择合适的介质材料厚度可保证损耗较低且电路体积不至于过大.

The selection of medium material and the parameter design has the key influence on the loss of pulse transmission line. According to distributed parameter theory and electromagnetic microwave theory, the computing formulas of loss of epoxy-glass-fiber (FR-4) and Polytetrafluoroethylene (F₄B) materials are given. When the characteristic impedance of microstrip is 50 W and the operating frequency is 10 GHz, the attenuation factor of medium of FR-4 and F₄B materials are respectively 0.095 dB/cm and 0.002 3 dB/cm. When the thickness of microstrip is 18 mm and the thickness of medium is 0.25 mm, the attenuation factor of conductor of FR-4 and F₄B materials are respectively 0.049 9 dB/cm and 0.035 7 dB/cm. The numerical computing and simulation results show that the loss of medium and conductor of F₄B material line is comparatively small, F₄B is a good medium material, and the lesser loss as well as not-too-big circuit-board can be assured by the appropriate thickness of medium material.