An Integrated Approach for Nitrate and Phosphate Detection using Squared SRR Microwave Resonator

This paper presents a novel microwave sensor for the detection of nutrients (phosphate and nitrate) in drinking water. The design of the proposed sensor is based on a square split-ring resonator (SSRR), which is tapered at the open end of the SSRR. Simulations were carried out for different relative permittivity values of sample placed in the active region of SSRR. Experimental measurements show the variation of transmission coefficient $(S_{21})$ and resonant frequency $(f_{r})$ of the SSRR for the liquid solution containing different concentration of phosphate and nitrate. Principle component analysis (PCA) was applied for classification of the liquid samples using the measured results. The proposed microwave sensing approach holds potential for diverse applications in biochemistry, medicine, agriculture, and environmental monitoring.