Adulteration detection in petroleum products using directly loaded coupled‐line‐based metamaterial‐inspired submersible microwave sensor

Abstract

A modified design topology of planar submersible sensor, to realize the improved sensitivity, using the split ring resonator (SRR) loaded coupled microstrip line is presented. The designed sensor can easily be immersed in the liquid sample under test. The maximum numerical sensitivity of the designed sensor (11.58%) at the design frequency of 6.12 GHz is quite higher than the sensitivity of earlier reported submersible sensor (4.01%). The measured unloaded resonant frequency of the fabricated sensor shows a close match with the corresponding simulated data. The fabricated sensor prototype can distinguish between the test samples having nearly similar dielectric properties due to its improved sensitivity. Two significant aspects of petrochemical industries in the Indian continent, i.e. contamination/blending of petrol with kerosene/ethanol are mainly considered here. As the discrimination between petrol and kerosene using the commonly available microwave sensors is especially quite challenging due to the very similar dielectric behaviour of these two chemicals. The developed prototype can typically measure the minimum 2% level of kerosene adulteration in petrol corresponding to 7.5 MHz shift in the measured resonant frequency. The uncertainty in the measured frequency shift of the liquid samples using the proposed sensor is found to be ∼1 MHz.