The Advanced Synthetic Aperture Radar (ASAR) is one of the instruments proposed by the European Space Agency (ESA) for use on the Polar Platform POEM-1 with a scheduled launch date of 1998. This phased-array radar comprises 320 transmit/receive (T/R) modules and therefore represents a high volume requirement for spaceborne applications. Each T/R module is required to meet stringent specifications in terms of size, mass, power consumption and overall electrical performance. This has been achieved through the widespread use of customdesigned, GaAs MMIC technologies within the module. Where high efficiency or low noise is required, discrete component circuits were used but methods of miniaturisation providing volumes comparable to that of packaged MMIC circuits were necessary. The project has also pioneered the use of lightweight packaging and substrate technologies for space applications.Demonstration of these techniques has set the trend for future remote sensing and communication payloads.