IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - IEEE AP-S/URSI 2026, Detroit (United States of America). 12-17 July 2026
Summary:
This work presents a low-cost microwave sensor for liquid-level detection in opaque dielectric containers, with particular focus on olive oil. The proposed approach is based on a Square Split-Ring Resonator (SSRR) placed inside the container, whose resonance is modified depending on the presence of the liquid. Contactless interrogation is achieved through axial Magneto-Inductive Wave (MIW) coupling with an external SSRR connected to a microstrip transmission line. The system operates using a simple amplitude-based detection scheme with a fixed-frequency excitation and a Schottky-diode-based detector, enabling a compact and low-cost implementation. Full-wave electromagnetic simulations demonstrate a clear difference in the transmission response between empty and liquid-covered conditions, resulting in distinct output voltage levels. These results validate the proposed concept and highlight its suitability for real-time liquid-level sensing in opaque containers using simple interrogation electronics.
Spanish layman's summary:
Se propone un sensor de bajo coste que permite detectar el nivel de líquidos en recipientes opacos, como el aceite de oliva, sin necesidad de contacto eléctrico directo. El sistema utiliza resonadores y técnicas de microondas para identificar si el líquido está presente, empleando electrónica sencilla y accesible.
English layman's summary:
This paper proposes a low-cost sensor capable of detecting the liquid level in opaque containers, such as those holding olive oil, without the need for direct electrical contact. The system uses resonators and microwave techniques to determine whether liquid is present, employing simple and readily available electronics.
Keywords: Microwave sensors; Split-Ring Resonators (SRR); Magneto-Inductive Waves (MIW); Liquid-level sensing; Opaque containers; Dielectric sensing
Publication date: 12-Jul-2026.
Citation:
F.J. Herraiz-Martínez, E. Alonso, J.D. Muñoz Frías, R. Giannetti, "SRR-Based Liquid-Level Sensor with Axial MIW Coupling for Opaque Containers", presented at IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - IEEE AP-S/URSI 2026, Detroit, United States of America, 12-17 July 2026
IIT-26-087C
