【作者】 延晓荣；

【导师】 钟顺时；

【作者基本信息】 上海大学 ， 电磁场与微波技术， 2008， 博士

【摘要】 为满足信息战电子对抗系统、电磁兼容和UWB无线通信等国民经济和军事应用的迫切需求,本论文对小型化超宽带印刷天线作了较深入的研究。针对天线的小型化、超宽的阻抗带宽、全向辐射特性以及带阻功能等需求,提出了多种不同结构形式的平面超宽带天线,并做了电磁仿真与实验验证。论文主要包括以下四方面创新性成果:(1)为了实现超宽带印刷单极天线,通过分析椭圆单极天线上的电流分布,提出了带孔的椭圆单极天线,并采用了由渐变到均匀的共面波导馈电形式。实测结果表明,天线获得了24.1:1的比带宽(VSWR≤2),覆盖频率范围0.44～10.6GHz,在工作频段上可实现较稳定的全向辐射。(2)为实现小型化和极宽带宽,提出了半椭圆单极天线,并将新型液晶聚合物(LCP)材料应用于印刷单极天线的设计中。通过分析主要参量对天线性能的影响以及优化设计,实验结果表明,半椭圆单极天线不仅具有25.7:1的驻波比不大于2的极宽带特性,在工作频段上实现较稳定的全向辐射,而且电尺寸较小,为0.21λ_l×0.11λ_l,其中λ_l为天线最低工作频率的自由空间波长。而采用LCP材料优化设计的天线,获得了超过30:1的极宽带宽,面积只有0.18λ_l×0.13λ_l,且更适合于与其它部件的电子封装及集成。(3)以椭圆单极天线为设计原型,提出一种新型的半单极印刷天线结构。通过分析优化结构参数及修正金属地板形状,设计出了物理尺寸为其原型天线43%的半单极印刷天线。测试结果表明该天线具有比带宽达25.9:1的极宽阻抗带宽和近似全向的辐射特性,测量的驻波比不大于2的阻抗带宽覆盖了从0.795GHz到20.6GHz频段。(4)为了避免UWB系统对无线局域网(WLAN)系统的干扰,通过在辐射贴片上开一个U形缝隙,设计了一种具有频带阻断特性的超宽带矩形印刷单极天线。缝隙各参数对频带阻断特性影响的分析表明,频带阻断特性可通过控制U形缝隙的位置来实现,而通过调整缝隙的长度和宽度可以改变所阻断频带的位置及带宽。实验结果表明所设计的天线实现了5.07GHz到5.85GHz的阻带特性,且具有阻抗带宽达15:1(0.595GHz～8.95GHz)的超宽带特性。更多还原

【Abstract】 To meet the urgent requirements of national economy and military applications for the electronic warfare systems,electromagnetic compatibility and wireless communications,etc.,this dissertation makes a deeper study on several types of UWB(ultra-wideband) and EWB(extremely wideband) printed antennas.According to the demand of miniaturization,ultra-wideband impedance bandwidth,omnidirectional radiation pattern and band-notched function of the UWB printed antenna,several novel designs are proposed and their experimental verification is completed.The main results are outlined as follows:(1) Based on the analysis of antenna current distribution,a hollowed elliptical Monopole antenna with a tapered coplanar waveguide(CPW) feeder is proposed.The experimental results demonstrate that the proposed antenna achieves a ratio impedance bandwidth of 24.1:1 for VSWR≤2,covering the frequency band from 0.44 GHz to 10.6GHz,and exhibits a nearly omnidirectional radiation pattern.(2) In order to realize the miniaturization and extremely wideband impedance bandwidth of the ultra-wideband printed antenna,a semi-elliptical Monopole antenna is proposed and the liquid crystal polymer(LCP) substrate is applied to the design of the printed Monopole antenna.The main parameters are analyzed and optimized using electromagnetic simulation.The experimental results demonstrate that the semi-elliptical Monopole antenna achieves a ratio impedance bandwidth of 25.7:1 for VSWR≤2,and exhibits a nearly omnidirectional radiation pattern,while its area is only about 0.18λ_l×0.13λ_l,whereλ_l is the wavelength of the lowest operating frequency.In addition,the simulated results demonstrate that the hollowed elliptical Monopole antenna with the LCP substrate obtains a ratio impedance bandwidth above 30:1,and is more suitable for packaging and integrating with other components.(3)A novel semi-Monopole printed antenna is introduced and a significant 43%reduction in size is realized by modifying and optimizing ground plane shape and other parameters.Experiment results show that the proposed antenna exhibits an extremely wideband impedance bandwidth,a nearly omnidirectional radiation pattern and a compact size.Its measured ratio impedance bandwidth for VSWR≤2 reaches 25.9:1,covering frequencies from 0.795 to 20.6 GHz.(4) To avoid the interference between the UWB system and the wireless local area network(WLAN) system,by cutting a U-shaped slot in the radiation patch,a compact rectangular Monopole antenna with a band-notch function is proposed.The slot parameters are studied in detail,showing that the band-notched function can be realized by control the location of the U-shaped slot and the notched band can be changed by adjusting the length and the width of the slot.Experimental results demonstrate that the proposed antenna has a stop-band of 5.07 to 5.85 GHz and a super-wideband from 0.595 to 8.95GHz(15:1) for VSWR≤2.更多还原