Wide Angle Frequency Scanning Antenna Design And Angle Measurement Algorithm Research

Compared with the phased array antenna,the frequency sweep antenna saves multiple T/R components under the condition of satisfying the scanning range,and has the advantages of low cost,simple structure,and easy to realize miniaturization;but the frequency sweep antenna achieves wide-angle scanning with the transmission loss is also large,the two factors contradict each other.In response to the current "black flight" of drones that poses a serious threat to national and social security,this thesis designs a wide-angle frequency sweep antenna for "low,slow,and small" target surveillance radars and produces and processes them for practical engineering,achieve the measurement of the target angle.This thesis introduces the basic theories of frequency swept array antennas and the radiation principle of waveguide slot antennas,various radiation forms and corresponding equivalent circuits.The basic structure parameters of frequency swept antennas are introduced and the calculation sequence and formula are given.By analyzing the index requirements of a certain frequency swept array antenna,firstly,the antenna structure parameter values that meet the project index are simulated in matlab,and then the parameters are optimized by module modeling and simulation in the electromagnetic simulation software CST,and finally the overall structure of the antenna is constructed for simulation.By adjusting the inclination angle of each waveguide slot,the radiation amplitude of each element of the antenna meets the Taylor distribution,the phase difference between adjacent elements is equal,and the side lobe of the antenna is reduced to below-20 d B.The antenna frequency scanning dimension achieves a large scanning range of-61.5°?47.5° in the 1.5GHz bandwidth,voltage standing wave ratio is less than 2,the beam width of the H plane in the working frequency band is in the range of 10° to 14°,and the beam width of the E plane at the center frequency point is less than 2.5°.The gain is greater than 28 d Bi,and the antenna isolation is less than-80 d B.The antenna was processed and its performance with or without a radome was measured in a microwave anechoic chamber.The test results showed that the actual performance of the antenna meets the design specifications.This thesis also studies the angle measurement algorithm in the azimuth dimension and the elevation dimension.In the azimuth dimension(frequency scanning dimension),the ratio angle measurement method is adopted.Introduced the working principle of the relative amplitude angle measurement,constructed the angle discriminating curve using the measured pattern of the frequency scanning antenna,and analyzed the angle measurement accuracy of the relative amplitude angle measurement.When the signal-to-noise ratio of the echo signal received by the lower gain beam of the two adjacent beams is about 10 d B,the angle measurement accuracy can reach one-tenth of the beam width,which is verified by the field test data;In the elevation dimension,this thesis gives the optimal parameters of the three-receiving channel frequency sweep radar with phase-comparison angle measurement.For frequency-swept radars with two receiving channels,this thesis proposes the amplitudephase comparison angle measurement method,and compares the angle measurement accuracy of the amplitude-comparison method,the phase-comparison method and the amplitude-phase comparison angle measurement method,and the signal-to-noise comparison is obtained.When the signal-to-noise ratio is low,the amplitude-comparison angle measurement method can be used to obtain a higher angle measurement accuracy;when the signal-to-noise ratio is high,the amplitude-phase comparison angle measurement method can be used to obtain a higher angle measurement accuracy.