And while the slow switching speed is a limitation in some High PRF radars, it suitable for medium and low PRF waveforms. So we are ready to examine an ESA which uses MEM phase shifters. They are of interest when detection requirements demand a large power-aperture product, but power is limited. Or when fire control accuracy demands small beam dimensions, but weight or power, or both, are limited. We will look first at constrained feeds for such arrays, and then look at space fed systems.
MEMs have an application to both.
Because of volume constraints, ESAs are typically built around a constrained feed manifold. The obvious advantage in this configuration is cost, but considerations of prime power consumption have frequently made the Active ESA the selected configuration. The characteristics of MEMs suggest we have a new look. A comparison of active element arrays and sub-arrayed passive ESAs using MEMs can be done by taking into account the losses and power consumption requirements of each alternative. These charts, which I will not discuss in detail, evaluate the total system power required for equal performance.