具有稳定高全向性的柔性宽带滤波单极天线
Flexible Wideband Filtering Monopole Antenna With Stable High Omnidirectionality
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中文总结 AI 辅助
提出一种带对称滤波结构的柔性宽带滤波单极天线，通过对称开槽等设计实现稳定高全向性，测试表明其带宽45.6%、带外抑制超11 dB，弯曲后性能稳定。
中文摘要 AI 辅助
本文提出了一种具有对称结构的宽带柔性滤波单极天线，以实现稳定的高全向性。该天线基于印刷在单层柔性基板上的单极天线设计，在驱动单极天线的两侧分别设置两条长度不同的折叠寄生条，无需额外滤波电路即可在高频段和低频段产生滤波响应。由于非对称滤波结构会对带内全向性产生不利影响，因此在基础设计中采用对称滤波结构以提升全向性和带宽。所提设计在单极天线的两侧对称设置一对寄生条，在高频段实现辐射零点；同时在带有开槽金属接地平面的馈线两侧加载一对折叠寄生条，在低频段实现辐射零点；此外，驱动单极天线还进行了对称开槽以实现宽带工作。通过采用全对称滤波结构，所提设计有效抑制了寄生元件对带内全向辐射方向图的影响，从而实现高全向性。此外，该天线在不同弯曲半径下均表现出稳定的性能。为验证设计理念，制作了天线原型并对平面状态和弯曲状态的天线进行测试，结果表明：该天线的-10 dB阻抗带宽为45.6%，带内增益约为2 dBi，带外辐射抑制超过11 dB；实测全向性在未弯曲时的变化小于0.8 dB，弯曲半径为30 mm时的变化小于1 dB。该设计具有多项优势，包括在宽频带上的稳定高全向性、柔性共形能力以及滤波特性。
英文摘要
This article presents a wideband flexible filtering monopole antenna with symmetric structure for stable high omnidirectionality. It is based on a monopole antenna, which is printed on a single-layer flexible substrate. Two folded parasitic strips with different length are devised on both sides of the driven monopole, giving filtering responses in the higher and lower band without filtering circuits. Since the asymmetric filtering structure adversely affects in-band omnidirectionality, this baseline design is extended with symmetric filtering structure to improve omnidirectionality and bandwidth. In the proposed design, a pair of parasitic strips are devised on the both sides of monopole antenna symmetrically, achieving a radiation null in the higher band. Then, by loading a pair of folded parasitic strips on the both sides of feed line with slotted metal ground, a radiation null is realized in the lower band. Besides, the driven monopole is slotted symmetrically for wideband operation. By adopting a fully symmetric filtering structure, the proposed design effectively suppresses the impact of the parasitic elements on the in-band omnidirectional radiation pattern, thereby achieving high omnidirectionality. Furthermore, the proposed antenna exhibits stable performance under different bending radii. To verify our design concept, an antenna prototype is fabricated. Both the flat and bent antennas are measured. The results show that the proposed antenna has a -10 dB impedance bandwidth of 45.6%, an in-band gain about 2 dBi, and an out-of-band radiation suppression more than 11 dB. The measured omnidirectionality has variations less than 0.8 dB without bending and 1 dB with a bending radius of 30 mm. This design offers several advantages including stable high omnidirectionality across a wide bandwidth, flexible conformal capability, and filtering property.
