High-frequency characterization of materials for microelectronics and design of antennas for biomedical and 5G applications

Keywords :
Microwave measurements, dielectric characterization, tunability, metamaterials, antennas, bio-based substrate

Abstracr :
The use of materials with well-known properties over a wide frequency range is of great importance in the microelectronics industry. For this, it is necessary to develop robust techniques for characterizing and extracting dielectric parameters in the microwave frequency range. As such, a method presented in this manuscript makes it possible to extract the complex permittivity of a material without the need for metallizations acting as electrodes. 
Indeed, some materials such as the integrated circuit encapsulation resin used to develop this technique do not have the technological maturity necessary to carry out these manufacturing steps. A reliability study is conducted via competition with another well-known method: the transmission line method.  
Radiating devices are also studied in this "HDR" report. First, an antenna for an application addressing the high band of 5G (26 GHz) is designed and measured. Ways to improve the gain and directivity of the antenna are discussed. Still in the same field of application, but this time at the more conventional frequency of 3.6 GHz for 5G, an antenna printed on a bio-based substrate is manufactured and measured. The radiating frequency of this antenna can be lowered to 2.4 GHz by activating a PIN diode. This demonstrator allows us to validate the use of these PIN diodes for the functionalization of a radome. Indeed, the possibility that we have to control the setting to the "on" state of the diodes makes it possible to control the  orientation of the beam emitted by the antenna. 
Finally, still in the field of antennas, an application to the biomedical field is presented. An antenna intended to be implanted subcutaneously to provide a telemetry function is presented. It has the characteristic of being dual-band, addressing the frequencies of 400 MHz (MICS band) and 2.4 GHz (ISM band). This antenna is manufactured and measured by immersion in a phantom whose dielectric parameters have been adjusted to match biological tissues in these frequency ranges. 

Jury members :

• Sonia DELMAS, University Professor, INSA Toulouse : President
•  Xavier CASTEL, University Professor, University of  Rennes : Rapporteur
• Christophe CRAEYE, University Professor, Catholic University of Louvain, Belgium : Rapporteur
• Bruno SAUVIAC, University Professor, Jean Monnet University, Saint-Etienne : Rapporteur
• Éric LHEURETTE, University Professor, University of  Lille : Examiner
• Bernard FLECHET, University Professor, University of Savoie Mont Blanc  : Examiner