Most current AESA radar systems use a small number of digitised receiver channels, but the next development involves carrying out the digitisation at the subarray level, or even the element level.
Several features of AESA technology boost the performance of a radar.
In a PESA, the incoming signal is initially passed through a passive component in the antenna array, but in an AESA, the active components are located before lossy passive components, so the noise figure is improved.
But in an AESA, these errors can be de-correlated across the distributed high and low-power amplifiers.
Since an AESA is based on solid-state electronics, the mean-time between failures (MBTF) is generally higher (better) than that associated with vacuum-tubes such as TWTs.
The very high signal levels associated with PESA require the use of mechanical waveguide switches, but AESA involves lower signal levels that can be handled by solid-state switches.
AESA antennas consist of a grid of transmit and receive (T/R) modules, spaced regularly on half wave-length centers.
The evolution of X-band AESA radar has been paced by several key technologies, but the emergence of MICs has been the latest and most important.
TI first developed the X-band modular electronics for radar application (MERA) AESA antenna in the early 1960s.
This program demonstrated T/R module reliability, as well as the inherent reliability of AESA architecture.
Building on the success of RASSR, beginning in 1983, the solid-state phased-array (SSPA) was the first USAF/TI X-band AESA array to realize the performance efficiency of direct power and receive amplification at X-band using GaAs devices.