射频同轴电缆特性阻抗的辨析
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摘要
由于特性阻抗是指电缆在理想均匀状态下传输线的始端电压和电流的比值,但实际生产中射频同轴电缆往往因制造公差而导致沿长度方向各点的特性阻抗不均匀,因此在实际中衍生出了局部(区域)特性阻抗Z_i、平均特性阻抗Z_m、输入阻抗Z_(in)三个阻抗概念。在概述Z_i、Z_m、Z_(in)三个阻抗概念及相应测试方法的基础上进行了辨析,并由相关实测值进一步验证了它们的差异性,以促使相关技术人员对这三个阻抗的正确理解及运用。
The characteristic impedance refers to the ratio of the voltage to current at the beginning end of the transmission cable,when the cable is in the ideal uniform condition.But in the actual production of radio-frequency(RF)coaxial cables,due to manufacturing tolerance,the characteristic impedance at each point along the length of cable is not uniform.So in practice,three impedance concepts are spawned,they are local(area)characteristic impedance Z_i,average characteristic impedance Z_mand input impedance Z_(in).The three impedances are discriminated on the basis of summarizing their concepts and corresponding test methods,and their differences are further verified by the relevant measured values.The results will be helpful to relevant technical personnel to correctly understand and apply the three impedances.
The characteristic impedance refers to the ratio of the voltage to current at the beginning end of the transmission cable,when the cable is in the ideal uniform condition.But in the actual production of radio-frequency(RF)coaxial cables,due to manufacturing tolerance,the characteristic impedance at each point along the length of cable is not uniform.So in practice,three impedance concepts are spawned,they are local(area)characteristic impedance Z_i,average characteristic impedance Z_mand input impedance Z_(in).The three impedances are discriminated on the basis of summarizing their concepts and corresponding test methods,and their differences are further verified by the relevant measured values.The results will be helpful to relevant technical personnel to correctly understand and apply the three impedances.
引文
[1]IEC.阻抗一致性试验(脉冲回波损耗/脉冲阶跃函数回波损耗):IEC 61196-1-115:2006[S].2006.
[2]IEC.金属通信电缆试验方法第1-1部分:电气用离散傅立叶逆变换(IDFT)在频域内测量脉冲/阶跃回波损耗:IEC 62153-1-1:2003[S].2003.
[3]IEC.射频电缆第一部分:一般要求和测量方法:IEC96-1:1986[S].1986.
[4]全国电子设备用高频电缆及连接器标准化技术委员会.射频电缆第1部分:总则,定义,要求和试验方法:GB/T 17737.1—2000[S].北京:中国标准出版社,2000.
[5]国防科学技术工业委员会.皱纹外导体半硬射频同轴电缆通用规范:GJB 1934A—2006[S].2006.
[2]IEC.金属通信电缆试验方法第1-1部分:电气用离散傅立叶逆变换(IDFT)在频域内测量脉冲/阶跃回波损耗:IEC 62153-1-1:2003[S].2003.
[3]IEC.射频电缆第一部分:一般要求和测量方法:IEC96-1:1986[S].1986.
[4]全国电子设备用高频电缆及连接器标准化技术委员会.射频电缆第1部分:总则,定义,要求和试验方法:GB/T 17737.1—2000[S].北京:中国标准出版社,2000.
[5]国防科学技术工业委员会.皱纹外导体半硬射频同轴电缆通用规范:GJB 1934A—2006[S].2006.