Abstract

T/R modules suitable for spaceborne SAR instruments have to fulfil very demanding requirements as given by the challenging environmental and electrical conditions in space. For this application a T/R module has been designed and realized which operates in X-Band and handles the temperature range from -20° to 60°C with full amplitude and phase stability. A low loss switch enables two polarisations alternatively or multiplexed in time. The output power of the module is 7 Watts over a wide bandwidth stabilized by a power control loop. The noise figure is as low as 3.2 dB. Amplitude control will be done by a phase stable variable gain amplifier (VGA), which is also used for temperature compensation. A 7-bit phase shifter is utilized for phase setting and phase compensation over temperature. The overall module efficiency at 10 % duty cycle is better than 18 % at ambient. This efficiency bases on radar mode operation, which means that the power consumption of the transmit path, receive path and the entire control electronic is taken into account. The paper will discuss the chosen architecture, critical components as well as the measured data of the T/R modules with respect to SAR system requirements. The paper will also give an outlook to advanced components and technologies for cost effective high volume production necessary for complete antenna integrations in the very near future.