Description
Date depot: 1 janvier 1900
Titre: Calibration of active antennas for radar application
Directeur de thèse:
Xavier BEGAUD (LTCI (EDMH))
Directeur de thèse:
Bernard HUYART (LTCI (EDMH))
Domaine scientifique: Sciences et technologies de l'information et de la communication
Thématique CNRS : Non defini
Resumé:
{{Scientific background}}::
Radars using electronic beamforming are composed of multiple (> 1000) radiating elements connected to the active components of the transmitter and receiver. The performance of these may drift over time and therefore monitoring of the antenna radiation is no longer controlled. It is therefore necessary to regularly calibrate transmission and reception channels to compensate for the drift.
Currently this calibration is performed by transmitting known signals in each channel by specific circuits (switches, couplers ...). The objective of this thesis is to seek alternatives knowing that the number of radiating elements increase but also the power of embedded digital processors.
One idea is to use the natural coupling between the elements of the network to replace the couplers. But this idea faces the problem of dynamic signals on transmission and reception channels. In general, for a radar operating mode (target far away from the radar), the transmission and reception channels of the radar does not operate at the same time. On the other side, it will not be the case during the calibration procedure : transmission and reception will operate at the same time. The consequence is that the power output can saturate strongly or destroy the reception channels.
A first research will be to calculate by an electromagnetic study the distance between the transmitter and the receiver in such a way to not estroy the receiver. But in that case the receiver will operate in saturation mode. It will then be possible to determine the non-linear transfer function between the transmission and reception channels. A second research is to estimate the linear function from the nonlinear function. This approach is completely new because usually reverse operation is performed, the nonlinear behavior of RF components is characterized cad (power amplifiers, mixers ...) by linear functions (Volterra series ....). It will require excellent background in mathematics and physics for this part to establish models and validate them by measurement.
Doctorant.e: Chalumyan Taguhi