Patent ID: 6359445
Filing Date: 2002-03-19
Classification: G01D

Abstract:
A microwave sensor for determining position or displacement of a movable mechanical part, said microwave sensor including a cavity resonator (40,70) for microwaves of a predetermined frequency, wherein said cavity resonator (40,70) comprises at least partly metal walls bounding a cavity (4,7) into which said mechanical part (2) extends, said cavity (4,7) being dimensioned for resonance of said microwaves at said predetermined frequency, and an antenna (14,8) arranged in the cavity (4,7) for reception of the microwaves in the cavity;wherein the mechanical part (2) has a metal end (3), the cavity (4,7) of the cavity resonator is dimensioned only for resonance of an H110 fundamental wave at said predetermined frequency of said microwaves, the cavity is circular-cylindrical and bounded by the at least partly metal walls, the metal end (3) of the mechanical part extends into the cavity, the cavity has a diameter (dmax, dmin) between 2.405â€¢c/&pgr;/f and 1.841â€¢c/&pgr;/f, wherein f represents the predetermined frequency of the microwaves input to the cavity and c represents the speed of light, and the cavity has a height of up to 0.4â€¢2.405â€¢c/&pgr;/f.