• W. Rammal, J. Rammal, M. Taoubi, J. Fouany « Microwave Technique for the Corrosion Detection », International Journal of Microwaves Applications, vol. 7, No. 2, pp 24-27, March 2018.

Abstract:

We present in this paper a new passive ceramic corrosion sensor which can be integrated into a structure submitted to a corrosive environment. The corrosion detection mechanism is based on the modification of a resonator frequency as a function of the corrosion level. An alumina substrate is covered with a metal enclosure that is protected against corrosion apart from the middle of the top face. This latter, patterned as a grid, is made of a metal sensitive to corrosion.

The cracks caused by the corrosion in the grid introduce a capacitive effect and cause a frequency shift of the resonance mode (fr), and a degradation of unloaded quality factor (Q0) as a function of the corrosion level.

 

• W. Rammal, J. Rammal, M. Taoubi, J. Fouany « Microwave Characterization of Dielectric Material at 2.45GHz », International Journal of Microwaves Applications, vol. 7, No. 2, pp 28-31, March 2018.

Abstract:

We describe a near field microwave microscopy method for characterization and rapid non-destructive imaging of dielectric materials samples at 2.45 GHz. This system is composed of a probe coupled to a dielectric resonator. It is used for two purposes: first to characterize dielectric samples with accuracy and high spatial resolution, knowing that they do not have predetermined forms but a small plane surface; and second, to draw dielectric cartographies for flat samples, with a 100 μm resolution.

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• J. Fouany, W. Rammal, M. Taoubi, J. Rammal « Modalisation of a circularly polarized directive antenna with parasitic elements for wide band applications », International Journal of Microwaves Applications, vol. 7, No. 2, pp 19-23, March 2018.

Abstract:

This paper present a directive circularly polarized wide band antenna with parasitic elements used for a wide band applications. To enhance the directivity and antenna band a distribution of parasitic dipoles is joined to a logarithmic spiral antenna to enhance the forward circular radiation over a bandwidth more than 20%. The electromagnetic responses of the parasitic dipoles are optimized thanks reactive loads welded on to the dipoles antennas.

 

• J. Rammal, F. Salameh, H. Mehdi « New Approach for Temperature Characterization of Low Loss Dielectric Materials », International Journal of Advances in Microwave Technology, vol. 2, No. 4, pp 136-140, November 2017.

Abstract:

This article presents a new technique for the characterization of low loss dielectric materials at high temperatures: the split cylinder resonator cavity. This technique allows the accurate characterization of the dimensional and electrical characteristics of the cavity and the electromagnetic properties of a dielectric material, simultaneously in one temperature cycle. To do this, the couple TE011+TE013 is used to characterize the sample and the couple TE012+TE014 is used to characterize the cavity conductivity and dimensions. Measurements of conductivity and dimensions using the couple TE012+TE014 for a loaded cavity at ambient temperature and during a thermal cycle show an agreement with the values obtained using the couple TE011+TE013 for an unloaded cavity at ambient temperature and during a thermal cycle. The characterization of an Alumina sample during a thermal cycle performed using the new technique and the traditional one shows a good agreement for the permittivities and the loss tangents.

 

• J. Rammal, F. Salameh, Wassim Rammal, Jamil Fouany, Hassan Mehdi « New Structure for Corrosion Evolution Detection », International Journal of Advances in Microwave and Technologies, vol. 3, No. 12, pp 141-145, February 2018.

Abstract:

This article presents a microwave sensor capable of detecting and following the evolution of the corrosion of zinc material. This sensor is based on zinc wires of different widths deposited on the surface of the ceramic resonator. Numerical studies show that due to the evolution of the corrosion, the progressive degradation of the conductivity of the formed zinc grid (from 6S/μm to 0.015S/μm) cause a progressive frequency shift (230MHz), a degradation of the quality factor (from Q0 = 50 to Q0 < 5) and a decreased level of the coefficient transmission of the TE101 mode of the resonator (from -8dB to <-35dB). Experimental measurements of this sensor in a corrosive environment show a gradual shift of the resonance frequency of the TE101 mode, a decreased level of S21 transmission coefficient and a degradation of the unloaded quality factor.

 

• J. Rammal, F. Salameh, O. Tantot, N. Delhote, S. Verdeyme « A Microwave sensor for zinc corrosion detection », Journal of Applied Physics, vol. 122, Issue 11, 2017.

Abstract:

This article presents a sensor based on zinc wires of different widths deposited on the surface of the ceramic resonator capable of detecting and following the evolution of the corrosion of the zinc material. Electromagnetic studies show that due to the evolution of the corrosion, the progressive degradation of the conductivity of the formed zinc grid (from 6 S/lm to 0.015S/lm) causes a degradation of the quality factor (from Q0 ¼50 to Q0 <5), a decreased level of the coefficient transmission of the TE101 mode of the resonator (from -8 dB to<-35 dB), and a progressive frequency shift (230MHz). Experimental measurements of this sensor in a corrosive environment show a gradual shift of the resonance frequency of the TE101 mode, a decreased level of the S21 transmission coefficient, and a degradation of the unloaded quality factor. Confirmed by electronic microscopy and X–Ray analysis, these variations are due to the evolution in the corrosion of zinc wires over time, leading to a creation of corrosion products in these wires.

 

• J. Rammal, O. Tantot, N. Delhote, S. Verdeyme, « Near Field Microwave Microscopy for the Characterization of Dielectric Materials » International Journal of Microwave and Wireless Technologies, vol. 6, pp 549-554, 2014.

Abstract:

In this paper, we present a near-field microwave microscopy method for the characterization of dielectric materials samples in the Industrial, Scientific and Medical (ISM) band. The system proposed is composed of a probe coupled to a dielectric resonator (DR) operating in the TE011 mode. Latter this is used to fix the resonance frequency of the resonator at 2.45 GHz. This system is used for the characterization of dielectric samples with accuracy and high spatial resolution, knowing that they do not have predetermined forms, but a small plane surface.The same device is used for a multi-frequency characterization (4– 20 GHz) using resonance frequencies of the cavity instead of one resonance frequency of the DR.