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International Journal of Antennas and Propagation
Volume 2017 (2017), Article ID 5619728, 13 pages
https://doi.org/10.1155/2017/5619728
Review Article

A Review of Sensing Strategies for Microwave Sensors Based on Metamaterial-Inspired Resonators: Dielectric Characterization, Displacement, and Angular Velocity Measurements for Health Diagnosis, Telecommunication, and Space Applications

CIMITEC, Departament d’Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

Correspondence should be addressed to Lijuan Su; tac.bau@us.naujil

Received 17 January 2017; Accepted 9 March 2017; Published 14 May 2017

Academic Editor: Mirko Barbuto

Copyright © 2017 Lijuan Su et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Four sensing approaches for the implementation of microwave sensors based on transmission lines loaded with metamaterial-inspired resonators are considered in this review paper, and examples of applications are pointed out. In all the cases, sensing is based on the effects that the magnitude under measurement causes in the transmission properties of the resonator-loaded line. Such four strategies are (i) resonance frequency variation, (ii) coupling modulation through symmetry disruption (causing variation of the notch depth), (iii) frequency splitting (also exploiting symmetry properties), and (iv) amplitude modulation of a harmonic signal. Such sensors are useful in various scenarios, of interest in fields as diverse as characterization of dielectric materials for communication circuits, medical diagnosis and treatment with microwave technologies, and sensors for space applications, among others.