The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 25, 2000
Filed:
Apr. 26, 1999
Endress + Hauser GmbH + Co., Maulburg, DE;
Abstract
For measuring the level of a material in a vessel by a radar-based method an antenna arranged above the highest level anticipated radiates electromagnetic waves to the surface of the material contained in the vessel and receives reflected echo waves. The transit time of the wanted echo waves reflected by the material surface is measured from which the level is computed. Since this transit time corresponds to the group delay, for determining the reduction factor by which the group velocity of the electromagnetic waves differs from the velocity of propagation in the free space due to the geometry of the propagation space the phase difference of the wanted echo waves relative to a reference oscillation and the group delay are measured for various levels and the reduction factor is determined on the basis of the changes in the phase difference as a function of the group delay.