The development of T/R modules for radar applications

The last 40 years has seen the migration from mechanically steered radars to the active electronically steered arrays (AESAs) of today. The key enabler for the AESAs has been the development and improvement of the performance, manufacturing capability, and cost of the Transmit/Receive (T/R) modules that typically sit behind each radiating element of the array. These T/R modules typically contain a duplexer (circulator), a driver amplifier and power amplifier for transmit, a limiter and a low noise amplifier for receive, and a common-leg-circuit used for both transmit and receive consisting of T/R switches, a phase shifter (for beam scanning), an attenuator, and a gain block. The first T/R modules were hybrid silicon-based modules developed for the MERA program which started in 1964. This talk traces the evolution from these first T/R modules through the development of the GaAs MMIC based modules of the 1990s and 2000s that power today's systems to the emerging GaN and silicon based modules of future active phased array radars. The evolution of the MMIC technology and capabilities as well as the improvements in assembly and packaging will be highlighted.