基于非均匀设计的高口径效率Fabry-Perot谐振腔天线

摘要

Fabry-Perot(F-P)谐振腔天线通常易实现高增益,但由于口径场非均匀的电磁场分布,使得其在大口径尺寸下的口径效率较低.本文设计了一种新型的F-P谐振腔天线,该天线采用非均匀特异媒质覆盖层实现口径场等幅分布,并通过非均匀特异媒质反射地实现口径场同相分布,从而提升F-P谐振腔天线在大口径尺寸下的口径效率.基于射线追踪法,推导了非均匀覆盖层和非均匀反射地的设计公式.本文设计、加工并测试了一款口径尺寸为5.18 λ(λ为自由空间波长)的圆形F-P谐振腔天线.仿真和测试结果吻合良好,|S11|<-10 dB的阻抗带宽为4.14%(5.740~5.980 GHz);在工作频点5.8 GHz处,该新型F-P谐振腔天线的增益为23.8 dBi,与传统F-P谐振腔天线相比,其口径效率从78.9%提高到90.5%.%Due to the non-uniform Electromagnetic(EM) field distribution over the superstrate,the Fabry-Perot Resonant Antenna(FPRA) is normally with high directivity but relatively low aperture efficiency when its aperture size is electrically large. A novel FPRA is proposed,both of whose superstrate and ground are designed to be non-uniform metamaterial, so as to realize the equal amplitude and cophasal distributions respectively for its aperture electromagnetic field, and thus enhance its aperture efficiency when its aperture size is electrically large. Based on the ray-tracing method, a set of formula for designing the non-uniform superstrate and ground are deduced. As a sample, a cylindrical FPRA with an aperture diameter of 5.18λ(λis the free space wavelength) is designed, fabricated and measured. Measured results agree well with simulated ones. It possesses an impedance bandwidth of 4.14%(5.740-5.980 GHz) when|S11|<-10 dB. At working frequency of 5.8 GHz,its directivity is 23.8 dBi. In comparison with a conventional FPRA with uniform superstrate and ground,the proposed FPRA increases the aperture efficiency from 78.9% to 90.5%.