EIRP and power efficiency of reconfigurable active transmit antennas

Reconfigurable, active transmit antennas are attractive for a variety of applications in the military and aerospace sector, since they offer antenna pattern flexibility via reconfigurable amplitude/phase control and permit high EIRP-figures with a set of amplifiers operating at fairly low power levels. Such antennas can be realized as direct radiating arrays, single-reflector multi-feed types or array-fed double reflector antennas (magnified arrays) and comprise, in all cases, a radiator section, a set of power amplifiers (PAs) and a low-power BFN. Looking from the systems perspective, one basic need for the handling of such antennas within the systems analysis and design is an antenna model which can be used for a wide variety of antenna types and provides easily usable tools for the prediction of the most relevant system figures. Whereas such a description for the gain and G/T of active receive antennas has been proposed in Kraft and Blaschke (1997), the current contribution provides a corresponding model for the EIRP and power efficiency of active transmit antennas where the antenna gain is almost meaningless.