交叉耦合馈电的小型化八臂缝隙螺旋天线

A Compact Eight-arm Spiral Slot Antenna with Cross-coupled Feeding

研究了一种应用于卫星导航终端的小型化交叉耦合馈电八臂缝隙螺旋天线。八条缝隙螺旋臂作为天线的辐射单元,蚀刻在FR4介质基板构成的方形柱状结构的外表面。馈电网络为上、下相互正交四分之三圆环的交叉偶极子微带线结构,延伸至了外表面且实现了交叉耦合馈电。天线尺寸为0.082λ0×0.082λ0×0.130λ0(λ0为中心频率1.561 GHz对应的自由空间波长),实测结果显示,|S11|≤-10 dB的阻抗带宽为1.554 GHz~1.591 GHz,3 dB轴比带宽为1.535 GHz~1.594 GHz。在北斗卫星导航系统B1频段中心频率(1.561 GHz)和全球定位系统L1频段中心频率(1.575 GHz)处的增益分别达到了2.56 dBi和2.75 dBi。该天线采用八臂缝隙螺旋和交叉偶极子臂耦合馈电相结合的结构,实现了较好的圆极化性能,同时具备宽频带和小型化的特点。

A compact cross-coupled feed eight-arm spiral slot antenna for satellite navigation terminal is proposed.Eight slit spiral arms are used as the radiating units of the antenna and are etched on the outer surface of a square columnar structure formed by an FR4 dielectric substrate.The feed network is a cross-dipole microstrip line structure with upper and lower mutually orthogonal three-quarter circles,which extends to the outer surface to realize cross-coupled feed.The size of the antenna is 0.082λ0×0.082λ0×0.130λ0(λ0 is the free-space wavelength corresponding to the center frequency of 1.561 GHz),and the test results show that the antenna has a-10 dB impedance bandwidth of 1.554 GHz~1.591 GHz and a 3 dB axial ratio bandwidth of 1.535 GHz~1.594 GHz.The gains reach 2.56 dBi and 2.75 dBi at the center frequency of the Beidou navigation satellite system B1 band(1.561 GHz)and the center frequency of the global positioning system L1 band(1.575 GHz),respectively.The antenna adopts a structure combining a crossed dipole arm coupled feed and an eight-arm slit helix to achieve a better circular polarization performance with broadband and compact size characteristics.