*The Present Situation and Development for Spaceborne Synthetic Aperture Radar Antenna… DOI: http://dx.doi.org/10.5772/intechopen.106040*

A major feature of the TanDEM-L program is the use of a combination of a deployable reflector antenna and a two-dimensional digital feed array (**Figure 16**). The left image is a technical solution proposed by DLR researchers to combine a reflector antenna and a two-dimensional digital feed array. In this scheme, the diameter of the reflector antenna is 15 m, and the feed source is a digital array of 36 (elevation) 3 (azimuth) and aligned horizontally. The scheme achieves a wide range and high gain in the distance direction by using the scanning processing concept of "Scan-On-Receive". Each of the pitch array elements consists of dual-polarized microstrip patches, and the signal from each polarization port is routed through the TR assembly and digitized in the corresponding DBF unit [58].

**Figure 16.** *Reflector and feed array of TanDEM-L.*

**Figure 17.** *Three azimuthal feed arrays antenna of TanDEM-L.*

This scheme achieves high resolution in azimuth by adding the feed array and azimuth beamforming technology in **Figure 16** along the azimuth. As shown in **Figure 17**, each feed array corresponds to an azimuth channel transformed to the ground, and the overall azimuth spectrum is recovered by beamforming technology.
