The scalable array module is the core of the open active phased array radar.

This paper introduces the development situation,constitution and operational principle of the active phased array radar systematically,analyzes and researches the application of active phased array radar on the early warning aircraft,lastly expects the application foreground and research trends of the active phased array radar on the early warning aircraft.

It also introduces the design of BIT system for one active phased array radar solid state transmitter in detail.

Some New requirements for active phased array radar and T/R modules are discussed in this paper.

Active phased-array radar, to receive communication signals,not only takes advantage of the high-gain characteristic of active phased-array radar antenna,but also makes another antenna unnecessary,thus reducing the cost.

Use of active phased-array radar antenna to transmit or receive communication signals, not only can greatly improve the communication system of data rate, but also to share communication systems and radar antenna and improve the integration, lower costs.

The composition and working mode of US terminal high altitude area defense(THAAD) are briefly described,the functions and characteristics of tactics and technology of solid state active phase array radar(SAPR) in THAAD are minutely analyzed.