Dual-Mode Equilateral Triangular Resonator With Slit for Material Sensing

This paper presents a dual-mode equilateral triangular resonator (DETR) sensor with a slit, which is theoretically analyzed and experimentally validated. In line with the theoretical analysis, the dual modes are the result of the rotation and superposition of the fundamental mode. A circuit model was developed tovalidate the theoretical analysis and good agreement was observed through a comprehensive comparison of results from full-wave simulations, theoretical calculations, and circuit model predictions. The proposed DETR operates in the industrial, scientific, and medical (ISM) band (902-928 MHz) and offers a unique communication link (or calibration) capability, making it a promising candidate for various applications. As a proof-of-concept, a prototype was designed, fabricated, and experimentally measured that confirmed the reliability of the sensor for material characterization. The results show that the higher frequency remains unaffected by distance changes between the sensor and receiver, whereas the lower frequency exhibits robust responses to various materials.