David Edwin Mays

US Patent:

62258125, May 1, 2001

Filed:

Jun 25, 1998

Appl. No.:

9/104661

Inventors:

David L. Mays - Woodstock GA
Ira B. Goldberg - Thousand Oaks CA
Charles S. Hollingsworth - Thousand Oaks CA

Assignee:

Rockwell Technologies, LLC - Thousand Oaks CA

International Classification:

G01N 2204

US Classification:

324634

Abstract:

A method and apparatus for measuring the amount of free water contained within a substance includes a waveguide having front and back sides disposed opposite each other. The waveguide defines a chamber for propagating a microwave signal therethrough. The waveguide has an end perpendicular to the front and back sides which forms a short within the chamber. The front and back sides each have an aperture for passing a substance therethrough. A microwave signal in the frequency range of 10-25 gigahertz is directed through the chamber wherein the generated microwave signal is reflected back from the short of the end. The generated and reflected signals form a ratio which is used by a microprocessor along with the measurement from an adjacent sensor that provides a dielectric constant measurement corresponding to the density of the substance in order to determine a weight of the substance compensated for free water.

US Patent:

56989865, Dec 16, 1997

Filed:

Feb 12, 1996

Appl. No.:

8/600076

Inventors:

David L. Mays - Woodstock GA
Ira B. Goldberg - Thousand Oaks CA

Assignee:

Allen-Bradley Company, Inc. - Milwaukee WI

International Classification:

G01N 2200
G01N 2700
H01P 710
H03H 900

US Classification:

324636

Abstract:

A cylindrical microwave cavity 12 has a pinched center 28, 30. Two apertures 28, 30, one in the center. of each face of the cylinder 10, provide access for a gas/powder mixture 124 having a dielectric coefficient depending on its density or some other measurement of interest. The faces 20, 22 of the cylinder 10 are much farther apart at the unpinched periphery, which comprises most of the volume of the cavity. The wider spacing allows an antenna 34 to be placed in the cavity 12, and provides a high Q-factor to maximize the sensitivity of the cavity 12. At the same time, certain resonance modes are greatly affected by a change in the dielectric coefficient of the gas/powder mixture 124 in the pinched portion 28, 30. The density of the powder or any other convenient variable may thus be servoed to any desired value. The powder 124 may be blown through the cavity 10, encased in tube 120 affixed to the cavity 12.