Antenna radiators for advanced active phased array SAR systems

Abstract:
The trend in modern SAR systems is towards higher bandwidths and hence improved range resolution. Besides wideband frontend electronics developing effort is also focused on the enhancement of antenna radiators which, in an active phased array SAR, have to satisfy both, wide bandwidth and high efficiency. In this paper an overview will be given on the current status of antenna radiator development for spaceborne SAR systems at EADS Astrium GmbH. The research is split into two different techniques: slotted waveguide and microstrip patch array. While the former is well known for its excellent efficiency and radiation purity innovations are introduced to overcome bandwidth limitations that come along with resonant structures. Thus bandwidths of up to 600 MHz in a dual polarised radiator configuration can be reached by application of alternative waveguide cross sections together with optimised slot dimensions. The microstrip patch with application of aperture coupling and corporate feed technique is commonly known as wideband design for dual polarised radiators in an active phased array antenna. Enhancements are achieved by adding stacked patches in order to obtain high bandwidth (>1 GHz) in combination with superb pattern purity and cross polar suppression.