Research Of Beam Steering Techniques In Optically Controlled Phased Array Antenna

Due to the restriction of aperture effect and the aperture traverse delay, it is difficult for a conventional phased array radar to get wide instantaneous bandwidth under wide scan scope. And then TTD (true time delay) is utilized in optically controlled phased array at sub-array level to replace the phase shifter in general phased array radar system to make time delay compensation at sub-array level, which abates aperture effect considerably and makes the broadband and wide-angle scanning of phased array antennas come true. So the research of OCPPAA is of great value, both in theory and in practice.In the first place , this dissertation introduces the basic theory of the scanning of antennas of the phased-array radar and the primary traits of the linear array antennas based on the structure of the phased-array radar, and analyses the instantaneous bandwidth of the phased-array radar.Secondly, this dissertation introduces the theory of sub-array phase shifting and the sub-array system of phased array which adopts optical true time delay. In view of the fact that, in the optically phased array radar, because the number of sub-array and the number of antenna unit in every sub-array is different , the performance of the phased array system will be influnced, the impact of the number of sub-array on the mainlobe deviation and the sidelobe level is analysed. Through analysis, a method of sub-array partition only based on the mainlobe deviation is presented, and this method is verified to be correct by computer simulation.Subsequently, considering the phase shifter is digital phase shifter in the optical controlled phased array antennas system, this paper simply narrate the theory of randomizing phase feeding, and analyses the demerit of two-probable number method randomizing phase feeding. To resolve instability of two-probable number method randomizing phased feeding result, a scheme of two-probable number method combining genetic alglrithms is put forward, which is simulated on the computer simultaneously. The simulating results show that this method can effectively reduces the instability of two-probable number method randomizing phase feeding result.