A Low-Cost Multiple Complementary Split-Ring Resonator Based Microwave
Sensor for Contactless Dielectric Characterization of Liquids
Abstract
We propose a low-cost, easy-to-fabricate, contactless microwave sensor
for dielectric characterization of liquids. The design of the proposed
sensor is based on a multiple complementary split-ring resonator (MCSRR)
fabricated on a low-cost FR-4 substrate. A glass capillary tube having
an inner diameter of 0.008λ0 is inserted in the high
electric field region of the MCSRR to carry the liquid under test. The
sensor is designed to operate at a resonant frequency of 2.45GHz for an
empty tube and shifted resonant peaks are utilized for the dielectric
characterization of different liquids. The maximum observed shifts in
resonant frequency and Q factor are up to 400MHz and 31, respectively.
The numerically established relations are experimentally verified
through fabricated sensor for various binary mixtures of water and
ethanol. The percentage errors between the calculated and reference
permittivity of different samples are noticed to be less than 5%. The
proposed device promises to be a cost-effective and convenient solution
for accurate dielectric characterization of liquids and their binary
aqueous solutions.