Passive UWB multiplexing device for a single-port MIMO RADAR
Résumé
MIMO radar imaging is receIVIng a substantial attention, thanks to its high resolution capacit y. Whereas, the complexit y and the cost of the active devices able to simul taneousl y transmit and receive signals of each antenna is a disincentive for the expansion of this technolog y , particularl y using UWB signals. In this paper, a passive device is presented to achieve MIMO radar imaging using a single-port reflection measurement. The conventional radar systems use an antenna array to achieve beamforming: the waves reflected on the scene to image are received by a single antenna for different beam steering and a time-angle image can be computed. Conversely, a single antenna can light the scene and the reflected waveforms gathered by the antenna array can be delayed and summed to achieve beamforming. Recently, a new technique using antenna arrays for the transmission and the reception has received a substantial attention [1][2]. Indeed, the use of a multiple-input multiple-output (MIMO) system for radar imaging allows an improvement of the image resolution compared to conventional beamforming techniques [3]. The spatial diversity of the medium is exploited through the low level of transfer function's correlation between each antenna. Thus, independent signals can be sent to each receiving element by all the transmitters. MIMO radar can be applied to a wide range of applications such as medical diagnosis [4], through-wall imaging [5] and concealed weapon detection [6]. Whereas, a complex architecture is required to reach this resolution, presenting as much transmitting and receiving systems as ports involved in the MIMO radar. In this paper, a single-port MIMO radar is introduced : by mean of a passive 1 x N device able to perform a compression in the physical layer of the waveforms received by an antenna array, MIMO radar imaging is performed with a single-port reflection measurement.