Rotation Sensor Based on the Cross-Polarized Excitation of Split Ring Resonators (SRRs)

A Reflective-Mode Phase-Variation Displacement Sensor

“…The reason is that in most microwave sensors devoted to the measurement of spatial variables, the output variable is typically a resonance frequency, a magnitude (of either a transmission or a reflection coefficient), a voltage amplitude, or a cumulative number of pulses, rather than a phase. Exceptions are the phase-variation sensors reported in [28], [29], but such sensors are devoted to the measurement of angular, rather than linear, displacements and velocities. Table I shows a comparison of various linear displacement sensors reported in the recent literature.…”

“…To alleviate the previous drawbacks of single-frequency coupling modulation sensors, phase variation sensors have been reported [25]- [29] (phase measurements are preferred over amplitude measurements in terms of noise). Phase variation sensors have been applied to the dielectric characterization of solid and liquids [25]- [27].…”

“…In such application, the working principle is the variation of the effective dielectric constant of a sensing line loaded with the material under test (MUT), which in turn modifies the phase of the line. The measurement of linear or angular displacements exploiting phase variation has also been demonstrated [28], [29]. For instance, in [28], the proposed sensor, based on a transmission line loaded with a rotating complementary split ring resonator (CSRR), takes advantage of the asymmetry of the sensor geometry and measures the angle of rotation in terms of the change in the relative phase of the reflection coefficients.…”

“…For instance, in [28], the proposed sensor, based on a transmission line loaded with a rotating complementary split ring resonator (CSRR), takes advantage of the asymmetry of the sensor geometry and measures the angle of rotation in terms of the change in the relative phase of the reflection coefficients. A similar approach was presented in [29], where the difference in the phase of the reflection coefficients of a slotline loaded with a rotatable SRR is the output variable (nevertheless, most SRR and CSRR based sensors have been applied to dielectric characterization [30]- [32]). In [28], [29], two-port measurement are required.…”

“…A similar approach was presented in [29], where the difference in the phase of the reflection coefficients of a slotline loaded with a rotatable SRR is the output variable (nevertheless, most SRR and CSRR based sensors have been applied to dielectric characterization [30]- [32]). In [28], [29], two-port measurement are required. In this paper, we report a single-frequency reflective-mode phase-variation sensor devoted to the measurement of linear displacements between the static part, an open-ended (i.e., one-port) step-impedance transmission line, and the movable part, a dielectric slab (other reflective-mode sensors, mainly devoted to material characterization, have been recently reported [33]- [36]).…”