一种波束赋形可调的导航天线设计

提供一种新的调节半功率波束宽度的思路，并设计了一款可实现波束宽度变换以应用于不同波束赋形场景的北斗二号B3频段的导航天线。基于四阵元双馈源的微带贴片天线阵列，在HFSS有限元仿真软件中根据理论进行建模仿真并优化。在保持右旋圆极化的基础上，不用改变阵列的结构，只需适当调节各个阵元激励的幅度与相位，就能实时缩小或者扩大半功率波束宽度，分别实现主瓣方向可调的定向波束赋形与宽波束赋形以应对不同的工作环境，并且具有定向抗干扰能力。仿真结果表明:定向波束赋形与宽波束赋形在B3中心频点的最大增益分别约为7.13，3.56 dBi，半功率波束宽度分别为52°，119°，3 dB轴比宽度分别为90°，166°；在整个B3频段内各个馈电端口反射系数低于?11 dB，相邻端口隔离度低于?28 dB。设计的波束赋形方式可调的导航天线适用于在无遮挡的开阔空间与特定的遮挡环境之间经常切换的工作场景，改善传统的机动式导航终端在“城市峡谷”等高遮蔽角环境下增益较低的缺点。

Design of navigation antenna with adjustable beam forming

A new idea of adjusting half-power beam width is applied to design a navigation antenna of Beidou-2 B3 band, which can realize beam width transformation and apply to different beam forming scenes. The microstrip patch array is modeled in HFSS simulation software. On the basis of keeping the right-handed circular polarization, the half-power beam width can be reduced or expanded without changing the structure of the array, the directional beam forming and wide beam forming with adjustable main lobe direction can be realized to cope with different working environments, and the directional anti-interference ability can be achieved. The simulation results show that the maximum gain of directional beam forming and wide beam forming at B3 center frequency is about 7.13 dBi and 3.56 dBi, the half-power beam width is 52° and 119° respectively, and the axial ratio width in xOz plane is 90° and 166° respectively. In B3 frequency band, the reflection coefficient of each feeding port is under ?11 dB, and the isolation degree of adjacent ports is under ?28 dB. The designed navigation antenna with adjustable beam forming mode is suitable for working scenes that often switch between open space without shielding and specific shielding environment, and it can improve the low gain of traditional mobile navigation terminal in the environment of high shielding angle such as “Canyon City”.