RF Imaging of Dielectric Samples Using Complementary Split Ring Resonator Array

Abstract

A microwave subsurface imaging scheme using a planar sensor based on an array of complementary split ring resonator (CSRR) is proposed. Conventionally, sensors based on single CSRR element are used for near field microwave imaging in which the sensor is made to scan the target region. However, while imaging larger test regions, sensor with multiple CSRR elements is extremely advantageous as it reduces the scanning time drastically by a factor that depends on the number of resonating units present in the array. The proposed sensor comprises of a 3×3 array of CSRR sensing elements, resonating at three different frequencies. The CSRR structures have a meandered configuration, possessing improved sensing capabilities compared to a conventional rectangular resonating unit of same dimensions. When the object to be imaged is placed on top of the CSRR structures, the sensor responds with a change in the transmission minimum frequency, with the shift proportional to the dielectric properties of the target region. The practical utility of the proposed scheme is established with the help of retrieved images of a checkerboard-like test sample.