Research On Broadband Shaped Patternfeeds For High Aperture Efficiency Compact Antenna Test Range

Compact antenna test range(CATR)is an important technology in the field of antenna testing.CATR can be able to generate quasi-plane waves in a small space,and is an effective method for measuring millimeter wave and terahertz band electrical large-sized antennas.The single reflector compact antenna test range system has received extensive attention because of its simple structure and considerable cost.However,due to the influence of mirror edge diffraction,the system’s aperture usage efficiency is low.Especially in the testing of large-aperture antennas,it is also limited by the level of mirror processing,which further affects the application of the single-reflection surface compacting field.In order to obtain a bigger quiet zone(QZ)under the same size of the main reflector,it is necessary to improve the aperture usage efficiency.To a certain extent,the edge diffraction effect can be reduced by designing the reflector edge method.However,the aperture usage efficiency is still low compared to the multi-reflector compact antenna test range system.Therefore,this paper will adopt the method of designing the shaped pattern feed to improve the aperture usage efficiency of the single-reflector compact antenna test range system.When using a single antenna to design a shaped pattern feed,due to the instability of higher-order modes,the shaped pattern formed by it is narrow in width.Thereby limiting the operating bandwidth of the measurement system.Therefore,increasing the shaped pattern bandwidth of the feed has become the focus and difficulty of this paper.This article introduces a solution to achieve high aperture usage efficiency in the wideband by designing patterned array antennas.In the design,use the improved particle swarm algorithm(PSO)for array synthesis.The three aspects of the inertial weight change method,particle flight speed and position control method,and fitness function setting strategy in the classic algorithm are improved to improve the algorithm convergence efficiency and calculation accuracy.Finally,multiple array antennas were designed.When coupling is not considered,3*3,4*4,5*5 element rectangular planar arrays and 5 element and 7 element single-loop circular planar array antennas composed of ideal point sources are designed.And considering the coupling conditions,the planar array of 5*5 element rectangular substrate integrated waveguide tapered slot antenna designed in combination with the active element pattern(AEP)method.The simulation results show that the five ideal point source arrays have achieved pattern fitting with small error.Moreover,real antenna arrays also achieve pattern shaping at 90 GHz,95 GHz,and 100 GHz.In order to verify the effect of the feed pattern of shaped pattern array,all the designed shaped pattern arrays are used as feed sources in the single-reflector compact antenna test range system for analysis.When the feed source is an array antenna composed of ideal point sources,aperture usage efficiency achieves more than 80%on the three intercept lines of 0°,45°,and 90°.This illustrates the effectiveness of the feed of the shaped pattern to improve the aperture usage efficiency.When the feed source is the 5*5 element rectangular substrate integrated waveguide tapered slot antenna array,the three intercept lines of the quiet zone at different operating frequencies can achieve the aperture usage efficiency greater than 74.5%.This enables broadband operation of the feed.The above results show that the array antenna can solve the problem of narrow working bandwidth of the shaped pattern feed,and has completed the research goal of this topic.