MIMO SAR Waveform Diversity and Design
This chapter discusses waveform diversity and design for multiple-input multiple-output (MIMO) Synthetic aperture radar (SAR) imaging. MIMO is a technique used in wireless communications to increase data throughout and link range without additional bandwidth or transmitting power. In MIMO SAR systems, each antenna should transmit a unique waveform, orthogonal to the waveforms transmitted by other antennas. For many years, conventional radars transmitted and received the same waveform, and processed that waveform identically on very pulse or burst within a coherent processing interval. Pulse compression techniques have been widely used in many modern radar systems. One of the early methods for pulse compression is by phase coding. A basic stepped-frequency waveform is a signal that breaks up the pulse width in time with a different frequency across each subpulse. It means that the subpulse’s frequency is uniform or fixed across the subpulse. Stepped-frequency waveform can imitate linear frequency modulation signal by linearly ordering the subpulse frequencies.