Digital Phased Array Radar

Phased array radars have been identified as the 'next generation' radars for many applications and demonstrator systems have been produced over the last few years for naval, ground based, airborne and civil applications. Great changes have taken place in digital technique at the same time. In order to improve the conventional phased array radar performance, the author presents a new type of phased array radars scheme that adequately applies digital technology to phased array radar.Full discussion is given in this paper according to the structure of conventional phased array radar. Key technologies are first introduced here such as the phased array antenna theory, DBF( digital beam forming) theory and the configuration of transmit and receive(T/R) modules. Then part of analog circuitry is optimized with the digital technology. Cell circular microstrip disk antenna successfully developed based on the theory of microstrip antenna, the four-celled circular microstrip disk antenna arrays are designed, simulated and analyzed with EDA tools-HFSS , OPT1METRICS. This paper goes on with analysis of the phased array radar calibration theory and compare of different schemes, then the best is adopted. 2 MHz digital circuit mainly composed of DDS(direct digital synthesis) chip, which carries out the shift of the phase and the limit of the amplitude, has been designed and debugged successfully. It is used to substitute for the conventional phased shift circuit and amplitude limiting circuit which work at the radio frequency, so the all-digital transmit channel of phased shift array radar is achieved.