System for moisture measurement at microwave frequencies
Abstract
Abstract APPARATUS FOR DETERMINING THE MOISTURE CONTENT OF GRANULAR MATERIALS SUCH AS WET WOOD CHIPS OR OTHER LOW DIELECTRIC, CELLULOSE BASED SUBSTANCES. THE SAMPLE MATERIAL UNDER TEST IS CLOSELY COUPLED THROUGH A SLOT IN A WAVE-L GUIDE TO THE ELECTRIC FIELD OF THE STANDING WAVE IN THE GUIDE. THE WAVEGUIDE IS DRIVEN BY A MODULATED MICROWAVE SOURCE, AND DIFFERENCES BETWEEN ENERGY INPUT AND ENERGY OUTPUT ARE MEASURED TO DETERMINE MOISTURE CONTENT IN T HE SAMPLE AS A COMBINED F UNCTION OF SAMPLE DIELECTRIC CONSTANT AND DIELECTRIC POWER LSS IN THE SAMPLE, THE PARTICULAR COUPLING ARRANGEMENT BETWEEN THE SAMPLE AND THE FIELD THROUGH THE SLOTTED WAVEGUIDE PROVIDING A CALIBRATION OUTPUT MEASUREMENT OF MOISTURE CONTENT WHICH IS SUBSTANTIALLY LINEAR OVER A RANG OF AT LEAST 2070% ON A WET WEIGHT BASIS, THE VARIATION IN OUTPUT READINGS AS A FUNCTION OF SAMPLE FILL FACT BEING SUBSTANTIALLY LOGARITHMIC AND, HENCE, SUBSTANTIALLY INDEPENDENT OF SAMPLE BULK DENSITY.
Inventors
- 👤 John W Lundstrom
- 👤 Marston D Mosteller
Bibliographic Details
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| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |