Research On UWB Dual-Polarization Probe For Near-field Measurement

With the rapid development of communication technology,antennas are playing an increasingly important role in the military and civilian fields,and the design requirements for antennas are becoming higher and higher.Antenna measurement,as an important method for analyzing and designing antennas,is an indispensable step in the field of antenna research.The high performance of antennas depends on precise measurement technology and supporting measurement systems.With the development of measurement technology,the research direction of antenna measurement has changed from far-field measurement to near-field measurement,and the near-field measurement data is processed through near-far-field transformation to obtain the characteristics of antenna radiation far-field.In recent years,in order to improve the accuracy of antenna measurement results,the near-field measurement system has been gradually updated,and higher requirements have been placed on the probe used for near-field measurement.In this paper,two ultra-wideband dual-polarization probes for near-field measurement are designed.The first type is a dual-polarized probe based on the traditional Vivaldi antenna.Firstly,a single-polarized Vivaldi antenna with a working bandwidth of 0.6-6GHz is designed through miniaturization techniques such as corrugated slot line loading and resistance loading.Within the working bandwidth,its voltage standing wave ratio is less than 2.3.The radiation pattern has good symmetry over the whole bandwidth.Then,under the condition that the structure of the feed network is complete,the two antennas are placed in a cross to form a dual-polarized probe.After optimization and simulation,the probe achieves a 0.6-6GHz frequency band,the voltage standing wave ratio is less than 2.4,the isolation between the two ports is greater than 30 d B,and the radiation pattern has good symmetry,which meets the design requirements.The second is a dual-polarization probe based on a Vivaldi antenna loaded with dual feed points.he traditional single feed point Vivaldi antenna is improved,and the double feed point structure is realized through two sets of slot lines and T-shaped power division networks that gradually follow an exponential curve,and the antenna is double-sided copper-clad and loaded with through-holes.Through the HFSS-ADS joint simulation,a PI-type structure is loaded on the initial structure to obtain a dual-feed point Vivaldi antenna,based on this,a dual-polarized probe with a working frequency band of 0.4-6GHz is realized.The diameter of the probe is 60mm*60mm,the voltage standing wave ratio is less than 2.0 in the frequency range of 0.4-6GHz,the isolation between the two ports is greater than 42 d B,and the radiation pattern of each frequency point has good symmetry.The two prototypes are manufactured and measured in a microwave anechoic chamber.In the 0.6-6GHz frequency band,the measured voltage standing wave ratio of the dual-polarized probe loaded with a single feed point is less than 2.4,the isolation between the two ports is greater than 28 d B,and the pattern symmetry is good.The measured voltage standing wave ratio of the dual-polarized probe loaded with double feed points is less than 2.0 in the 0.4-6GHz frequency band,and the isolation between the two ports is greater than 42 d B,which is consistent with the simulation results,and the pattern has good symmetry and the main lobe beam width is wide.The above measurement results show that the dual-polarization probes designed in this article have good electrical performance,and the second probe has been used in a multi-probe measurement system.