Research On Correlation Interferometer Direction Finding Antenna System

In order to adapt to the interference protection in the battlefield environment and environmental monitoring in the civil field,the application of radio direction finding is increasingly widespread.The correlation interferometer direction finding technology,which has a high precision,is an important and common radio direction finding system with high direction finding accuracy.In this thesis,the correlation interferometer direction finding antenna system is investigated.The main contexts and contributions are shown as follows:The correlation interferometer direction finding algorithm is introduced.The algorithm is simulated and realized with the software of Matlab.The differences between two kinds of correlation coefficient calculation formulas are discussed as well as the accuracy of the direction finding at different frequencies.Antenna elements suitable for the correlation interferometer direction finding system are designed.First of all,on the basis of the research of traditional disc monopole antennas,an ultra-wideband spherical monopole antenna which operates from 500 MHz to 6 GHz is proposed.The antenna has a spherical radiator structure and a stepped impedance matching structure,which is compact and easy to manufacture.Then,two kinds of ultra-wideband planar monopole antennas based on coplanar waveguide feeding structure are presented respectively.Both of the two antennas work from 200 MHz to 6 GHz.For reducing the lower limit of the operating frequency,the designs of triangular ground plane and elliptical slotted structures are adopted.Finally,an ultra-wideband monopole antenna with lumped inductive and resistive loading is put forward.This kind of antenna achieves an impedance bandwidth from 20 MHz to 5 GHz,and the electrical size at the lower limit of operating frequency is only 1/15 wavelength.And particularly,it has a better performance than that of the commercial antenna.A simplified direction finding antenna system is constructed by one of the planar monopole antenna designed before,and the direction finding experiment is carried out.The experimental results demonstrate that the azimuth angles of the incoming signals can be accurately located,and the practicability of this direction finding antenna system is verified.