Design And Implementation Of Phased Array Antenna Signal Generator Based On DDS

In 1960s, with the emergence of phased array radar, the study of phased array antenna became very important in phased array radar domain. To generate phase controlled waveform is the key of phased array antenna study. With the development of micro-electronics and modern digital technology, phase controlled signal generated by digital technology has gradually taken the place of traditional analog method. Digital phase control technology can realize precise, programmable and highly stable waveform output. As for waveform output of phased array antenna, digital phase control technology has become the most important way of phase control.This paper studies the phase controlled multi-channel video signal generator as well as the design of the S-band phased array antenna system based on that video signal generator. The paper also studies the local oscillator so as to afford 2GHz output.First, with the basic principles of phased array antennas, this paper illustrates the relationship between phase control and the maximum radiation direction of phased array antenna. Then, based on the digital frequency synthesis technology, this paper shows several frequency synthesis methods. Through comparing the differences between these methods, this paper picks a frequency synthesis approach based on DDS at last and analyzes the principles of DDS in detail. With AD9912 as the core, this paper realizes hardware design of the multi-phase digital video signal generator. At the same time, this paper also achieves phase control and frequency control of DDS board through the USB interface of computer, as well as hardware design of the local oscillator. Finally, this paper analyzes the waveform and spectral purity of the video signal generator and output waveform of local oscillator. The video signal generator designed based on DDS has many virtues, including fast frequency switch, highly precise phase control, flexibility and easy to use. Waveform phase is controlled by 14-bit digital control word and this control word can be generated by MCU or computer that has been designed to send 14-bit digital control word to control waveform phase through the USB interface.These have the control process be flexible and good compatibility. This paper uses AD8302 to measure multi-channel video signal phase differences, and achieves the through closed-loop feedback with control board. In the end, the paper realizes capturing the phase information and controlling the phase synchronization of the output signal.