4D-arrays for MIMO radar applications

A novel approach for multiple-input multiple-output (MIMO) radar applications is proposed, namely four-dimensional orthogonal frequency (4D-OF), which applies the technique of four-dimensional arrays (4D-arrays) and frequency stepping. The sidebands of the 4D array are utilized to generate multiple orthogonal carrier frequencies and transmit signals. The time sequences are optimized by the differential evolution (DE) algorism to synthesize a desired radiation pattern with a better directivity compared to frequency division MIMO. A linear FM (LFM) pulse signal is input to the 4D array and is spread at the center frequency and a few sidebands in the same direction. An analytic expression for the cross correlation function of these sideband signals is presented to study the relationship between pulse duration and time-modulated frequency. Without the use of numerical mixers, the 4D-OF is a good candidate for the MIMO radar. Some simulation results are presented to demonstrate the effectiveness of this method.