Kamel Frigui

Microwave Breakdown in Waveguide Filters Theoretical and Experimental Investigations

This paper deals with undesirable microwave breakdown phenomenon that can appear in output multiplexer filters for telecommunications satellites. The first objective was to improve the theoretical investigation of the phenomenon by improving the accuracy of the breakdown numerical modeling based on a combination of three fields of science: electromagnetism, thermal transfer theory and plasma physics. The second objective was to validate the theoretical modeling by experimental tests. A specific structure has been designed and built and a dedicated measurement procedure has been proposed. As it will be shown, the test structure experimental behavior agrees well with the theoretical one. Consequently, the proposed numerical modeling of microwave breakdown is validated.

CNTs effects on RF resonators printed on paper

Low-cost RF resonators are reported to be formed from silver nanoparticles and carbon nanotubes (CNTs) printed on a paper substrate, operating at high frequency. The fabrication technique can be versatile in order to obtain a thin Ag layer and thin films of CNTs on the same substrate. Ag layer metallization is sprayed as the conductive part of the device achieving the transmission. CNT films are printed on one specific spot of the resonators to explore the electromagnetic effect of CNT films on the resonant circuits. Depending on the location and the density of CNTs printed, the CNTs act on the electromagnetics coupling to perform the transmission of the resonators or interact on the frequency.

Microwave breakdown in waveguide filters, numerical simulation, and comparison to experiments

Microwave breakdowns in output multiplexer filters, boarded on telecommunications satellites, can affect the device and damage it. During tests at atmospheric pressure, these breakdowns are generally initiated in the vicinity of a noble metal coated frequency adjustment screw. A modeling of the microwave breakdown ignition is developed taking into account the thermoelectronic emission from the screw and the noble metal atom vaporization. The influence of field strength is particularly investigated to predict the breakdown delay after the application of the microwave power. Then, a specific structure has been designed and built and a dedicated measurement procedure has been proposed. As it will be shown, the test structure experimental behavior agrees well with the theoretical one. Finally, the results given by the numerical modeling of microwave breakdown are compared to the measurements performed in a five-pole filter of an output multiplexer.

Theoretical investigation of microwave breakdown ignition in OMUX filters. A 3D numerical modeling approach

A description of microwave breakdown in output multiplexer filter is presented in this paper. Such a phenomenon can affect the device and cause irreversible damage. It is so necessary to be able to predict the power level which can generate such a microwave breakdown. To study this problem, a multidisciplinary approach with a combination of three fields of science was used: electromagnetic, thermal transfer theory and plasma physics. In this paper new 1D and 3D numerical investigations of microwave breakdown in OMUX filters are presented.

Impact of CNT-film printed on conformal resonator on paper

Printed electronics is one of promising technology to make passive microwave circuits, which can be manufactured using traditional inkjet-printing tools at low temperature fabrication and a low cost production. In the present study, we report a tunable microwave resonator depending on the density of carbon nanotubes (CNT) printed in thin layers. The whole module is realized by inkjet printing on paper substrate and designed by finite-element simulations using HFSS to operate around 30 GHz. The resonator is firstly printed by Ag ink and then the CNT films are printed on a specific place of the resonator, which we can control the electrical conductivity by tuning on the density printed (from 3.49 to 27.9 CNT/μm2), and resulting in the variation of the frequency resonance of the resonator. The electrical performance characterization of the resonator printed is reported, and demonstrated two different states, one state called “ON” and one state called “OFF”.

One dimensional numerical modelling of microwave breakdown in OMUX filters

A theoretical investigation of microwave breakdown in output multiplexer filters is presented. In order to model this phenomenon a multidisciplinary approach with a combination of three fields of science was used: electromagnetism, thermal transfer theory and plasma physics. In this article we resume the theoretical study and we present our results, on determination of breakdown appearance and on influence of various parameters on this phenomenon.

Capacitive microwave sensor for toxic vapor detection in an atmospheric environment

This paper presents an inkjet printing capacitive microwave sensor for toxic vapor detection. The designed sensors were presented and fabricated with success. The experiments show sensitivity to ethanol vapor according to the S parameters. It is equal to 0.9 kHz/ppm and 1.3 kHz/ppm for the sensors based on 5 and 50 sensitive layers respectively. This sensor will be integrated into real-time multi-sensing platforms adaptable for the Internet of Things (IoT).

Numerical modelling and characterization of the microwave breakdown in OMUX filters

This paper deals with the microwave breakdown phenomenon that can appear in output multiplexer filters for telecommunications satellites. In order to model this phenomenon a multidisciplinary approach with a combination of three fields of science was used: electromagnetism, thermal transfer theory and plasma physics. In this article we resume the theoretical study and we present our experimental validation.