MIMO-FM: A Solution to Estimate Target Elevation with Passive FM Radar

In this paper, we deal with the problem of estimating the target elevation in passive FM radar. Due to the large wavelength of such systems, accurate beamforming at the reception side would require unpractical large reception devices of several meter height. We instead propose to solve this problem by means of a MIMO-like system that exploits the vertical structure of large existing FM broadcasters transmitting different frequency subbands with antennas located at different heights. We provide the MIMO-FM ambiguity function in that context and details the specific reception processing enabling to retrieve the elevation parameters. The feasibility of such a MIMO-FM system is proved on real data experiment using transmitting antennas located on the Eiffel Tower in Paris.