| 摘要 |
<p>A non-contacting method of measuring the electrical resistance per unit length of a filament (10), such as a carbon-coated optical fibre, makes the filament the inner conductor of a co-axial transmission line and measures a propagation characteristic of that line. The transmission line may be dived into seven sections (80, 81, 82, 83, 84, 90, 91 and 84), with a signal injected on the second section, and a comparison of the resulting signals appearing on the fourth and sixth sections being used in a feedback loop to control the injected signal frequency in such a way as to hold constant either the relative amplitudes or the relative phases of the signals appearing at the fourth and sixth sections.</p> |
