MIMO Methods Applied in Over-the-Horizon Radar Figure 13. (a) Range-Doppler map that shows the single waveform backscatter clutter response with multiple propagation modes (1E-1E, 1E-1F2l, 1F2l-1E, 1F2l-1F2l) present that obscure much of low Doppler space (+/-0.5 Hz). (b) Range-Doppler map showing the backscattered clutter corresponding to the modeselected 1E-1E path for the same data as in Figure (a). (c) A second mode-selection example from the same data set. The range-Doppler map shows the backscattered clutter corresponding to the mode-selected 1E-1F2l path. (d) A third mode-selection example from the same data set. The range-Doppler map shows the backscattered clutter corresponding to the mode-selected 1F2l-1E path. (e) A final mode-selection example from the same data set. The range-Doppler map shows the backscattered clutter corresponding to the mode-selected 1F2l-1F2l path. 66 IEEE A&E SYSTEMS MAGAZINE DECEMBER 2017