In the antenna research group planar multilayer antennas have been developed for this application. Figure 1 shows the architecture of a C-band element in multilayer technology. The coupled radiators with different size (stacked patches) yield a bandwidth of about 10%. The feed for both polarizations is made by a cross slot aperture. A metallic groundplane shields the antenna to the backside. Figure 2 depicts a CAD model of the whole array and Figure 3 the printed boards of the different layers.