粗细电缆低反射系数连接器阶梯电容的补偿设计

电缆与电缆连接器端面处不可避免地会出现机械段不连续,形成阶梯电容,干扰电磁波的正常传播,使得电缆与连接器的相应连接端面处反射系数增加。依据电磁波传输理论、射频电缆的参数理论和电缆连接器阶梯电容的错位补偿原理,推导出了电缆连接器高抗补偿绝缘垫片厚度的相对普适公式。针对电缆连接器与射频同轴细电缆SYV-50-7和射频同轴粗电缆SYV-50-17连接之间阶梯电容约0.1pF的情况,理论计算补偿绝缘垫片厚度应约为2mm,应用中可通过加工多个补偿厚度尺寸与理论计算值相邻的绝缘垫片,并在实际安装时进行调节,从而最终确定绝缘垫片的最佳补偿厚度。可以预见,合适的实验验证和优化,可使电缆与连接器端面连接处的阶梯电容减少,甚至消除,综合特性阻抗与电缆和连接器均匀一致,反射系数小于0.8%是可能的。

The Compensation Design for the Step Capacitance in the Low Reflection Factor Connector for Thick and Thin Cables

In the end face of a cable and a connector,mechanical discontinuity is inevitable,which will cause a step capacitance and disturb the normal transmission of electromagnetic waves,leading to the increase of reflection factor at the end face.Based on electro-magnetic transmission theory,RF cable theory,and the vicarious compensation principle of cable connector,a relatively universal formula is derived out for the high reactance compensation of the insulator thickness of the connector.According to the fact that the step capacitance of the connection between coaxial connector and thin coaxial RF cable（SYV-50-7） and thick one（SYV-50-17） is about 0.1 pF,the thickness of the insulator should be about 2 mm.In practical application several insulators whose compensation thicknesses are near theoretical calculation values may be fabricated for adjustment in practical mounting,thereby determining the optimal compensation thickness of the insulator at last.As an inference,it is possible to make the reflection factor of this kind of connectors to be lower than 0.8% if proper optimizations are achieved to reduce or even eliminate the step capacitance at the end face of the connector.