1. A method for detecting an electromagnetic signal, called signal of interest, likely to be contained in an electromagnetic signal received by an antenna array comprising a plurality of antenna elements, said method comprising the following steps: applying to said electromagnetic signal received by each antenna element a plurality of time-frequency transforms in order to obtain a representation of said signal in the form of a plurality of time-frequency cells each containing the spectrum of said signal for a given frequency interval and a given time interval, for each time/frequency cell of a given set of cells, calculating the energy of the vector made up of the spectra over all of the antenna elements, applying the following nonlinear function T to the result of the preceding energy calculation, so as to cancel the time/frequency cells containing substantially only noise: if the norm of the energy of the vector of the spectra is below a first predetermined threshold s, the result of the function T is zero, if the norm of the energy of the vector of the spectra is above or equal to said first threshold s, the result of the function T is equal to the norm of the energy of the vector of the spectra minus the value of said first threshold s, integrating, over said set of time/frequency cells, the result of said nonlinear function T, comparing the result of the integration to a second predetermined threshold, called detection threshold S det , to detect the presence of the signal of interest.