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IEVref: | 726-07-01 | ID: | |

Language: | en | Status: Standard | |

Term: | characteristic impedance (of a transmission line or waveguide) | ||

Synonym1: | |||

Synonym2: | |||

Synonym3: | |||

Symbol: | |||

Definition: | a quantity defined for a mode of propagation at a given frequency in a specific uniform transmission line or uniform waveguide by one of the three following relations:
|I^{2}Z_{2} = ||U^{2} / SZ_{3} = / UI
where the complex power and S and U are the values, usually complex, respectively of a voltage and a current conventionally defined for each type of mode by analogy with transmission line equationsIExamples:
1. — For a parallel-wire transmission line, can be uniquely defined and the three equations are consistent. If the transmission line is lossless, the characteristic impedance is real.I
2. — For a waveguide, the conventional definitions for depend on the type of mode and generally lead to three different values of the characteristic impedance. I
3. — For a circular waveguide in the dominant mode
4. — For a rectangular waveguide in the dominant mode | ||

Publication date: | 1982 | ||

Source: | |||

Replaces: | |||

Internal notes: | 2017-08-30: Corrected the order of the <i> and <u> tags. LMO | ||

CO remarks: | |||

TC/SC remarks: | |||

VT remarks: | |||

Domain1: | |||

Domain2: | |||

Domain3: | |||

Domain4: | |||

Domain5: |

*Z*_{1} = __ S__/ |

where __ Z__ is the complex characteristic impedance,

Examples:

1. — For a parallel-wire transmission line, __ U__ and

2. — For a waveguide, the conventional definitions for __ U__ and

3. — For a circular waveguide in the dominant mode *ТЕ*_{11}, *U* = r.m.s. voltage along the diameter where the magnitude of the electric field strength vector is a maximum, *I* = the r.m.s. longitudinal current.

4. — For a rectangular waveguide in the dominant mode *TE*_{10}, *U* = the r.m.s. voltage between midpoints of the two conductor faces normal to the electric field strength vector, *I* = the r.m.s. longitudinal current following on one surface normal to the electric field strength vector.