| 摘要 |
<p>A microwave densitometer comprises a phase difference detecting section (25) for detecting a phase difference between a microwave generated from a microwave generator (33) and a microwave received by a microwave receiver (32), a rotation number updating section (41) for varying a value of number of rotations "n", a correcting section (36) for obtaining a difference value DELTA &thetas; indicating a difference between a true phase difference &thetas;2 and a reference phase difference &thetas;1, a signal converter (38) for converting the difference value DELTA &thetas; to a concentration signal an operation mode setter (39) for setting a operation mode, and a holding circuit for holding the number of rotations "n" and the apparent phase difference &thetas;2' when a concentration measuring operation of the fluid to be measured is switched to a non-measuring operation in response to a change of the operation mode set to the operation mode setter (39). <MATH></p> |
