A Phased Array System Based On Optical Fiber True Time Delay Network

With the rapid developments of optoelectronics, signal processing technology and computer science, optically controlled phased array antenna emerged. The core technology of optically controlled phased array antenna is optical true time delay technique. On the basis of a detailed understanding of optically controlled phased array antenna and optical true time delay system, a phased array system based on optical fiber true time delay lines is designed and produced.The system includes 8 groups of ordinary optical fiber delay lines corresponding to eight different beam direction angles. Each group contains eight optical fibers whose length is in arithmetic progression. Different optical true time delay can be produced by the optical fibers with different length. The cutting accuracy of the optical fiber is ± 0.4mm.The system adopts the optical switch to convert the direction angle. A controlling circuit is designed to control the optical switch. Besides that, a system operation interface is writed with three main functions:single channel gating, circular scanning and roundtrip scanning.In addition, a DC stabilized power supply with 12V/1A is made as power supply for the optical switch and the controlling circuit. The output voltage ripple is below 50mV when the power supply is tested under rated load. Its conversion efficiency is greater than 80% and it has good output voltage stability.Finally, an instrument container for the system is fabricated. Test results show that the error of the direction angle of the system is within ± 0.33 °. The inequality of the phase and the output power is within the range of allowable error. The 1 dB compression power point is larger than 10dBm at 10GHz.