This paper presents a novel strategy for the implementation of highly sensitive reflective-mode (one-port) phase-variation permittivity sensors based on coupled resonators (the sensing elements). It is demonstrated that by tuning the frequency of the feeding harmonic signal in the vicinity of the resonance frequency of the isolated resonators, and by weakly coupling the resonant elements, the phase of the reflection coefficient (the output variable) experiences a significant variation with the dielectric constant of the material under test (MUT), resulting in a high sensitivity.
