一种基于开口谐振环的高增益端射天线设计

A design of high-gain end-fire antenna based on split-ring resonator structures

基于开口谐振环(split-ring resonator,SRR)奇异的电磁特性,设计并制备了一种覆盖C和X波段的高增益SRR-Vivaldi端射天线.采用等效分析方法对SRR结构谐振特性进行了研究,并将其应用于传统Vivaldi天线指数渐变槽线前方,使SRR结构形成特殊谐振能力的引向器,将天线表面电流集中于端射方向,在保证天线尺寸和带宽不变的前提下,实现了天线增益的有效提升.仿真和测试结果表明,新型SRR-Vivaldi天线在C波段增益平均提高75.44%,xoy面和xoz面半功率波束宽度都缩减20°以上;在X波段增益平均提高24.46%,xoz面半功率波束宽度大约缩减25°.该结构具有低成本、设计简单、便于加工、利于共形等优点,为端射天线提高增益和增强定向性提供了新思路.

Vivaldi antennas have wide applications in practice due to the ultra-wide band properties; however,their gain and directivity are relatively low.In this paper,a new method is presented to improve the gain and directivity of Vivaldi antennas in a broad band using split-ring resonator（SRR）.Based on the peculiar electromagnetic properties of SRR,a novel high-gain SRR-Vivaldi end-fire antenna in C and X bands is designed and fabricated.The size of the antenna is only 0.33λ × 0.33λ × 0.013λ,a significant miniaturization.Equivalent analysis method has been adopted to study the resonance characteristic of an SRR structure.By adding the SRR structures the singular metamaterials in the front of the Vivaldi antenna have an exponential taper slot,and the SRR structures can play a role as a director which has the ability to enhance the antenna’s directivity so that the surface currents will focus on the end-fire direction.The SRR structures have been analyzed,designed,and fabricated,which can be embedded into the original Vivaldi antenna smoothly and compactly.As a result,the gain of the SRR-Vivaldi antenna are enhanced effectively,while the size and bandwidth of the original antenna can be kept,with the reflection coeffcient less than-10 dB from 4 to 13.6 GHz after using SRR.The novel Vivaldi antenna based on the SRR has good features of high gain,high directivity,low return loss and low cross-polarization.Compared to the original Vivaldi antenna,the simulation and measured results demonstrate that the gain of the novel SRR-Vivaldi antenna in C band has been increased by an average value of 75.44% and the half-power beam width has been decreased by 20 degrees in xoy and xoz planes.Meanwhile,the gain has been increased by an average value of 24.46% in X band and the half-power beam width has been decreased by 25 degrees in xoz plane.Testing result of the fabricated antenna demonstrates the reliability of the design.A good agreement between simulations and measurements is obtained.The design owns the merits of low cost,simple design and ease in fabrication and conformation,thus provides a new idea for end-fire antenna gain and directivity improvement.The new antenna has great potentials in applications.