MIMO radars and their conventional equivalents - an update

Abstract

It had originally been shown in the literature that a MIMO full/thin array radar system (consisting of a full transmit linear array of N elements having λ/2 spacing and a collocated, parallel, linear thinned receive array having Nλ/2 spacing) is equivalent to a full array of N2 elements having λ/2 spacing and thus achieves N times the accuracy and resolution as a conventional full array of N elements, 10 times or 100 times or 1000 times better than a conventional array depending on N [1]. It has since been shown that a conventional array radar can do as well as a MIMO full/thin array radar [2]. Specifically, a conventional full/thin array radar was shown to provide the same resolution and accuracy as the MIMO array. The conventional full/thin array had some disadvantages relative to grating lobes that had to be dealt with but in some situations it could provide better energy search efficiency than its MIMO equivalent. Here a new conventional array is presented which has no grating lobes, the same resolution and about has the same accuracy as the MIMO full/thin array radar. Also it uses the same search time and about the same power-aperture product to do volume search as the MIMO radar. The new conventional array consists of the same full and thin arrays but with their roles reversed with the thin array transmitting and the full array receiving. The new conventional array is called a thin/full array to distinguish it from the former full/thin array. The properties of the full/thin and thin/full MIMO and conventional array radars are detailed relative to waveforms and matched filter signal processing loads. The matched filter processing load for MIMO full/thin and thin/full arrays are dependent on whether the transmit or receive beam forming is done first. It is pointed out that MIMO radar systems do not have any advantages relative to barrage jammer, hot clutter jammer or repeater jammer suppression. Finally it is shown how the conventional thin/full array can be used for GMTI so that it should provide the same minimum detectable velocity as does the MIMO thin/full array.