A six-band microstrip sensor, based on a pair of electrically coupled resonators (ECRs), is proposed to perform multifrequency dielectric characterization of liquids. A pocket is milled through the substrate bottom of the sensor to contain the fluid sample, avoiding the need for a sample holder. The pocket has been designed to achieve a higher electric field magnitude in the sensing region and a mechanism to separate the resonant frequencies, which helps to ensure a high span between the first and the last resonant frequency. The microstrip sensor is implemented on a 1.905-mm-thick substrate with $\varepsilon ^{\prime }_{r} = 12.2$ and $\tan \delta = 0.0019$ . The sensor’s six resonance frequencies span the range between 1 and 3.5 GHz. Experimental tests show that the sensor can measure a wide range of $\varepsilon ^{\prime }_{r}$ values between 2 and 79 resulting in close similarities to the dielectric constants published in previous works.

In this work, a sensor in microstrip technology and a methodology for measuring the real part and the imaginary part of the complex uniaxial permittivity of solid anisotropic samples are presented. The sensor is based on a pair of parallel lines coupled resonators and a cleft arranged in the coupling region which allows to hold the samples under test (SUTs). The proposed methodology relates the change in the even/odd resonance frequency with the real part of the permittivity in the vertical/horizontal direction, and the change in the Q factor of the even/odd mode with the imaginary part of the permittivity in the vertical/horizontal direction. The methodology was successfully verified with the characterization, at 2.43 GHz of anisotropic samples of printed PLA, Diclad 880, and RO4350B using the knowns materials: RT5870, PTFE and RO4003.

In this letter, a new sensor, theory, methodology, and experimental results of dielectric constant characterization of several planar samples under test (SUT) are presented. Each SUT is placed over a microstrip sensor that is based on a pair of electrically coupled resonators (ECRs). The proposed method determines the dielectric constant by using the electric coupling coefficient ( $k_{e}$ ) of a pair of coupled half-wavelength open-loop resonators. The methodology was successfully tested over a wide dielectric constant value substrates at 2.5 GHz, with substrates Diclad 880, Rogers 5870, Rogers 4003C, TMM10i, and Rogers 6010 resulting in high-accuracy percentages of 99.22%, 99.21%, 99.56%, 97.68%, and 98.60%, respectively.

In this work, a methodology is presented for the determination of the respiration rate of a person under test (PUT), the detection of movements, as well as the elimination of the spurious effects produced by the movements of the PUT. The methodology is based on Empirical Modal Decomposition (EMD) applied to the phase signal obtained by means of a quadrature Doppler radar operating in S band. The EMD allows to automatically eliminate the continuos component (CC) which is present in the phase signal since one of the main characteristics of the modes generated by the EMD is that its mean is equal to zero. On the other hand, the first mode of the EMD is used for the detection of movements while the sum of the second and third modes are used for the elimination of the CC drift caused by the DC drift and the high frequency components produced by the movements of the PUT. The proposed methodology was successfully tested in a PUT at rest and performing movements of the head, arm and combination of head, arm, and torso. The average respiration rate measured was 20.78 breaths / min with a standard deviation of 2.53 breaths/min.