A method for obtaining an angle-Doppler signature for a target using sparse arrays in multiple-input-multiple-output (MIMO) radar, the MIMO radar including a transmit antenna array, the transmit antenna array being at least one-dimensional (e.g. 2-D, 3-D or 4-D) and having a plurality of antenna elements. The method includes generating transmit signals for transmission by the transmit antenna array, the transmit signals defining at least a first transmit trajectory (e.g. circular) of a phase center within the transmit antenna array, and transmitting the transmit signals using Amplitude Modulation on the transmit antenna array. The method further includes receiving receive signals from the target, the receive signals resulting from the incidence of the transmit signals upon the target, and determining the angle-Doppler signature from the receive signals. The first transmit trajectory is such that, in operation, the phase center undergoes non-linear motion within the transmit antenna array.