A metamaterial sensor for detecting the location of a sub-wavelength object

Abstract

A metamaterial sensor is proposed to detect the random location of a sub-wavelength metallic object. The sensor is composed of a transmission line (TL), which supports the propagation of spoof surface plasmon polaritons (SSPPs) with localized electromagnetic (EM) field, and a complementary spiral resonator (CSR) that resonates strongly at designed frequencies around 0.9 and 2.7 GHz. Based on the shift of the resonance frequencies, this sensor is able to detect the location of a sub-wavelength metallic object (whose diameter is smaller than 0.6 mm) randomly attached to the CSR. A prototype of the sensor is fabricated and tested. In practice, the CSR is excited through the EM coupling of the SSPP TL, and the location of the metallic object is obtained through the transmission coefficient (S21). To improve the accuracy, a retrieval curve for locating is generated and calibrated. It is proved that the random location of the sub-wavelength object can be accurately detected inside an area of 9π mm2 with a low error of 2‰.