介绍了一种超宽带低剖面天线设计,该天线由弯折偶极子、短路寄生结构、接地短路柱、同轴电缆和金属地板构成。给出了天线的设计过程,说明了各部分结构对天线性能的影响。该天线通过加载短路寄生结构,减小了偶极子臂上电流分布,减小了地板对天线的影响,实现了低剖面特性。此外,该天线通过将偶极子中间部分弯折,改善了高频段的辐射方向图。最终,该天线尺寸为750 mm×450 mm×295 mm,剖面高度仅为0. 09 个低频波长。为了验证天线设计思路的正确性,加工了天线实物。文中给出了天线仿真与测试的电压驻波比以及增益的结果,其测试结果与仿真结果相吻合。该天线在96 MHz~500 MHz(135. 57??)频段内电压驻波比小于2. 2,并且在该频段内具有定向辐射的方向图,增益大于3. 38 dBi。

A design of ultrawideband and low-profile antenna is introduced in this paper. The proposed antenna is consists of a bending dipole, two parasitic shorted walls, a shorted metal cylinder, a coaxial cable, and a metal ground. This paper gives the design process of the proposed antenna, which illustrates the effect of each structure on the antenna performances. By using the parasitic shorted walls, the current distribution on the arms of the dipole is reduced which reduces the influence of metal ground on the performance of the proposed antenna, and then the low-profile performance is realized. In addition, the radiation patterns of higher band are improved by bending the middle of the dipole. Consequently, the proposed antenna has an overall size of 750 mm×450 mm×295 mm. The profile of the proposed antenna is only 0. 09λ,where λ is the free-space wavelength at the lowest frequency. To illustrate the validity of antenna design, the antenna model is fabricated. This paper gives the measured and simulated results of antenna VSWR and gain. Good agreement between the measured and simulated results is observed. The impedance bandwidth for VSWR<2. 2 can cover the band of 96 MHz-500 MHz(135. 57??). In addition, in the working band, the radiation patterns of the proposed antenna are unidirectional, and the measured results are in good agreement with the simulated ones.

TN820