Digital Theses Archive


Tesi etd-09092019-202548

Type of thesis
A Photonics based Multiple Input Multiple Output Coherent Radar Network for Maritime Surveillance and High Resolution Applications
INGEGNERIA - Ph.D. Programme in Emerging Digital Technologies (EDT)
Presidente Prof.ssa BOGONI, ANTONELLA
  • Automotive radar
  • Coastal surveillance
  • Distributed radar network
  • High resolution radar
  • Maritime surveillance
  • MIMO radar
  • Multi-band radar
  • Multi-static radar
  • Photonics-based radar
  • SAR radar
Exam session start date
New generation radar systems have to ensure higher resolution standards in order to support sophisticated applications such as target imaging or autonomous driving. Conventional monostatic radars are unable to ensure upcoming performance requirements, due to spectrum erosion and unsolved technological issues existing in the radiofrequency (RF) domain, especially related to high fractional bandwidth management. Recently, an innovative class of radars, referred to as Multiple Input Multiple Output (MIMO) radars, has been proposed that essentially performs data fusion on multiple radar signals acquired in spatial diversity. Although aforementioned multi-static radars have manifold benefits, among which also a remarkable resolution capability, until now, demanding system requirements have prevented their outspread. In the last decades, research conducted in the field of Microwave Photonics has led to the development of reliable techniques that allow an effective RF signal distribution over long distances, generate RF signals having an excellent phase stability and manage ultra-wide bandwidth signals as well. Accordingly, a largely distributed centralized coherent radar network can be conceived based on optimal signal distribution operated in the optical domain. Eager to know the robustness of the envisaged architecture, as a first step, a numerical analysis has been conducted by the means of a self-developed MIMO scenario simulator. From the analysis executed on different operative scenarios the superiority of phase coherent detection is evident. Furthermore, outcomes fully confirm that a photonics-based centralized network architecture can easily meet coherent MIMO system requirements. Therefore, first a MIMO 2 transmitters (TXs) x 2 receivers (RXs) photonics-based demonstrator has been implemented and tested in a down-scaled outdoor scenario and following a 2 TXs x 4 RXs configuration in an indoor scenario. In the last part of the dissertation, the outcomes of previously mentioned experimental activities are reported in detail. The results are very promising as a collaborative target has been detected with a 15 times better localization precision with respect to the range resolution descending from the employed signal bandwidth and a resolution capability as low as 10 cm has been assessed, witnessing a 50 times angular resolution enhancement compared to the angular resolution associated to large aperture antennas used for the test. Nontheless further aspects need to be better investigated as, for instance, the sidelobe drawback intrinsic to MIMO operations as well as reliable multi-static RCS models, the remarkable results obtained definitively prove the effectiveness of the proposed photonic approach and, more generally that photonics could result an enabling technology for the development of next generation MIMO radar networks with widely separated antennas.