Moisture sensor using helical transmission line
US5818241A · kind A · utility
Inventor
Key dates
| Filing date | May 30, 1996 |
| Grant date | Oct 6, 1998 |
| Priority date | — |
| Expiry date | May 30, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/121
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Moisture sensing apparatus that uses slow wave transmission lines. Such transmission lines include a helically wound inner core, a surrounding outer conductor, and a moisture bearing material between the inner core and the outer conductor. Preferably, the transmission line includes a moisture barrier that separates the transmission line into a sealed dry section and a wet section which is in moisture communication with its environment. The moisture sensing apparatus further includes a source of electrical signals on the transmission line, and a moisture sensing circuit, operatively connected to the slow wave transmission line, which senses the moisture content of the moisture bearing material from the velocity of the impressed electrical signals on the slow wave transmission line. Preferably, the velocity of the impressed electrical signals is obtained indirectly using a sing-around measurement technique.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.