This chapter presents a novel fully active digital beamforming technique for radar remote sensing that is based on the concept of multidimensional waveform encoding on transmit. In contrast to the aforementioned techniques, the full area of the antenna aperture is used for both the transmission and the reception of radar pulses. This enables an improved SAR imaging performance while relying on the well established transmit/receive (T/R) module technology. The mandatory expansion of the antenna beam width for wide area illumination is achieved by an innovative spatiotemporal modulation of each transmitted radar pulse. The modulation introduces angular waveform diversity in the transmitted signal and provides, thereby, in the recorded radar echoes additional information about the spatial scatterer distribution. The multidimensional waveform encoding is hence the natural complement to digital beamforming on receive, and the combination of both techniques enables a wealth of new SAR imaging modes that significantly increase the performance, flexibility, and adaptability of future radar systems and missions.

Inspec keywords: radar imaging; receiving antennas; image coding; synthetic aperture radar; spaceborne radar; array signal processing; transmitting antennas; multidimensional signal processing; radar antennas; remote sensing by radar

Other keywords: transmit receive module technology; radar pulse; antenna beam width; antenna aperture; SAR imaging performance; multidimensional waveform encoding; spatial scatterer distribution; spaceborne synthetic aperture radar remote sensing; angular waveform diversity; active digital beamforming technique; wide area illumination

Subjects: Single antennas; Radar equipment, systems and applications; Image processing and restoration; Geophysical techniques and equipment; Image and video coding; Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research