A microstrip defect ground structure (DGS) based on a pair of dumbbell-shaped slots is used for sensing. The device is a differential sensor consisting of a pair of mirrored lines loaded with a dumbbell-shaped DGS, and the output variable is the cross-mode transmission coefficient. Such a variable is very sensitive to asymmetries in the line pair, e.g., caused by an asymmetric dielectric load in the dumbbell-shaped DGSs. Therefore, the sensor is of special interest for the dielectric characterization of solids and liquids, or for the measurement of variables related to complex permittivity changes. It is shown in this work that by adding fluidic channels on top of the dumbbell-shaped DGSs, the device is useful for liquid characterization, particularly for the measurement of solute concentration in very diluted solutions. A sensitivity analysis useful for sensor design is carried out in this paper.
In this letter, composite right/left handed transmission lines based on complementary split ring resonators are applied to the design of dual-band microwave components. Specifically, impedance inverters operative at two (arbitrary) different frequencies (one of them within the left-handed band and the other within the right-handed band) are designed and applied to the implementation of a dual-band branch line hybrid coupler. The characterization of this device reveals good performance and dual-band operation. The fabricated device is small, fully planar, and vias are not required. Index Terms-Complementary split ring resonators (CSRRs), composite right/left handed (CRLH) transmission lines, dual-band components.
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