摘要 : Microwave resonant cavities have been studied as possible sensors for rapid determination of the mass or weight of perturbing dielectric objects of given permittivity and density, but of arbitrary shape, inserted into the cavity. ... 展开 Microwave resonant cavities have been studied as possible sensors for rapid determination of the mass or weight of perturbing dielectric objects of given permittivity and density, but of arbitrary shape, inserted into the cavity. Tracking the coordinates of the peak of the resonant curve with and without the object, i.e. measuring shift of resonant frequency and change in the cavity Q-factor, provides information that together with a calibration equation is sufficient for the object mass or weight determination. During the calibration procedure, the parameters of the empty cavity, as well as the permittivity and the specific gravity of the object material must be known. The measurement technique does not, in principle, require any contact between the object and the measuring system, and measurements can be rapid and reasonably accurate. Basic principles of the shape-independent measurements are presented, and experimental results are given for common plastic objects of irregular shapes measured in resonant cavities operating at 640 MHz and 1.7, 2.5 and 3.2 GHz. [References: 15] 收起