Remote Measurement of Dielectric Constants for Samples with Arbitrary Cross Sections

Measurements of dielectric constant are of significant importance. Existing methods, contact or noncontact, require the sample under test (SUT) with a specified dimension. It can be the cross section of a rectangular waveguide or a regular-shaped reference SUT. In this work, a new approach extended from microwave imaging is proposed to remotely measure the dielectric constants of 2-D SUTs with arbitrary cross sections. An algorithm based on scattering integral equations is derived for an efficient parameter retrieval. Experimental measurements based on a time-division bistatic multiantenna system were conducted. It is verified that by deriving an inverse scattering problem-based algorithm, the dielectric constants of such SUTs can be effectively retrieved from the scattering data detected by a measurement setup previously designed for microwave imaging, regardless of the complexity of their cross sections. The proposed approach can be readily applied to various 2-D samples such as dielectric section bars. It can also be conveniently extended to 3-D samples in the future.