Design Of Full Polarization RF Front-end And Antenna

Polarization information is used to describe the vector characteristics of electromagnetic wave,which is an important information available for wireless communication.With the development of polarization information research,it has great potential in the field of wireless communication and radar.The accuracy of target recognition can be improved by introducing polarization information extraction and analysis into radar system.In wireless communication,polarization diversity technology can be used to resist multipath fading and improve channel capacity.As the hardware foundation of polarization technology application,the realization of full polarization of RF transceiver system will be the future development trend.In this paper,a set of full polarization RF transceiver system is designed and implemented.The specific research content is divided into three parts:1.A fully polarized transmitter is developed.Based on the analysis and comparison of the traditional transmitter structure,the whole polarization transmitter system architecture is built.The transmitter consists of frequency synthesizer module,transmission channel module,control module and power module.The gain,frequency selectivity and harmonic characteristics of the scheme are simulated by ADS software.The experimental results show that the frequency modulated continuous wave with controllable bandwidth can be produced by the full polarization front-end.The polarization mode can be changed by switching the SPDT switch.The transmitting power is 25.33 d Bm,and the spurious suppression is-70.39 d Bc @ 4.27 GHz.2.A fully polarized receiver is developed.Based on the research of receiver system architecture,the receiver front-end adopts superheterodyne structure,which consists of local oscillator module and receiver channel.A special low-noise design is carried out according to the requirements of the index.It is verified by simulation and measurement that the noise figure of the full polarization receiving front-end is 1.2d B,and the phase noise of the receiving local oscillator is-97.16 d Bc/Hz @ 1 k Hz.3.A fully polarized antenna is designed to fit the full polarized RF front-end.The antenna is a cross dipole structure,which consists of a planar dipole patch,an L-shaped feed structure,a parasitic element,a dielectric plate and a reflecting floor.By changing the feeding mode,we can realize the conversion of linear polarization and circular polarization,and parasitic elements are introduced to realize beam broadening.HFSS software is used to simulate and verify the fully polarized antenna.According to the distribution of surface current,the principle of dual polarization is analyzed.The experimental results show that the beam width of the antenna is more than 120° and the port isolation is more than 30 d B.The fully polarized radiation characteristics are realized by changing feeding.