Research On Key Technologies In Microwave Photonics Beamforming Network

Microwave photonics is a subject which combines optical technology and microwave technology.Microwave photonic technology uses optical method to process microwave signal,which brings the advantages of optical technology such as large bandwidth,low loss,reconfigurability into microwave signal processing system.The key technology phase shifter and photonic arbitrary waveform generator in microwave photonic beamforming network are studied in this thesis.For microwave photonic phase shifter,a new phase shifter technology based on polarization modulator is proposed.This technology not only has the advantages of traditional microwave photonic phase shifter technology based on polarization modulator in phase shift range,amplitude response and phase tuning speed,but also fills the gap band of 2-26.5 GHz.At the same time,we also analyze the ripple problem of the output RF signal frequency response of the microwave photonic phase shifter using a 90? hybrid coupler in detail,and propose an effective solution,using cost-effective optical filters to improve the frequency response performance of the output RF signal,and verified through experiments that the maximum amplitude and phase fluctuation of the output RF signal of the phase shifter are reduced from 4.2dB and 12 degree to 2.2dB and 3.5 degree in the frequency band of 4-40 GHz.For microwave photonic arbitrary waveform generator,a microwave photonic arbitrary waveform generator based on frequency shifting loop is proposed.Compared with the traditional electrical arbitrary waveform generator,this technology not only has the characteristic of arbitrary waveform reconfigurability,but also realizes the function of multiplying the output waveform by simple operation.In this paper,we show several commonly used waveforms: triangular wave,frequency doubling triangular wave,forward sawtooth wave and reverse sawtooth wave.