Soil moisture sensor
US4540936A · kind A · utility
Assignees
Inventor
Key dates
| Filing date | Sep 7, 1982 |
| Grant date | Sep 10, 1985 |
| Priority date | — |
| Expiry date | Sep 7, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R27/2605
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A moisture sensor including in one embodiment a probe formed with a first cylindrical tube extending outward from a base and having a plurality of axially extending slots around the periphery thereof and a second slotted cylindrical tube extending outward from the base separated and insulated from the first tube, and extending coaxially with the first tube. The tubes form an effective coaxial capacitor and are insertable into material to be sensed appear as a ground plane. In a second and third embodiment a member defining flat surfaces extends from a base forming in cross-section a volume with a square center and legs extending from each side thereof to an open peripheral end. An RC bridge circuit, preferably a Wien bridge or a capacitor divider circuit is connected to the tubes to measure the impedance of the material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.