一种新型宽带高增益多模导航天线设计

Design of New Broadband High-Gain Navigation Antenna

为了适应多模导航卫星系统的发展,文章设计了一种新型宽带高增益导航天线,能够覆盖北斗B1/B3、GPS L1/L2频段。天线采用折叠电磁偶极子的形式,具有较宽的阻抗匹配带宽。为提高圆极化辐射特性,采用四馈点形式,等幅度、相差90°馈电;端口直接激励到交叉十字形馈电结构,进而耦合到折叠偶极子,辐射圆极化电磁波。天线周围加入调试腔体,可对方向图辐射特性进行调整,且具有宽带高增益的特性。方向图在北斗B1/B3、GPS L1/L2频段内具有良好的一致性。在三维电磁仿真软件ANSYS HFSS中,建立天线的三维仿真模型,并进行仿真计算,在工作频段内,电压驻波比VSWR≤1.5,主辐射方向上交叉极化比不小于40dB,具有良好的圆极化纯度。在整个工作频段内,天线具有低后瓣特性,前后比不小于40dB,且右旋圆极化增益在主辐射方向图±60°范围内,不小于0dB,在多模卫星系统上具有较高的应用价值。

In order to adapt to the development of multimode navigation satellite system,a navigation antenna with high gain is introduced in this paper,which can work in the bands of BD2 B1/B3,GPS L1/L2. It is a magneto-electric dipole antenna whose impedance bandwidth is wide.In order to realize the circularly polarized characteristics with high gain and directional radiation pattern, four feeding ports are studied.Ever feeding port is set with equal amplitude and 90 degree phase difference.A special feeding structure is proposed in the antenna,which can ensure energy couple to the novel folded dipole antenna. Due to the constant radiation pattern requirement in engineering application,a circular cavity is designed to adjust the radiation beamwidth of the antenna.the antenna above can meet wide impedance and high gain radiation pattern along the operation bandwidth.A simulation model is established in 3 D electromagnetic simulation software ANSYS HFSS.In the working frequency range,the Voltage Standing Wave Ratio(VSWR) is less than 1.5,what’s more.The cross polarization ratio of the antenna is more than 40 dB,which leads to good circular polarization characteristics.As a directional antenna,it has a low back lobe characteristic,and the front to rear ratio is more than 40 dB.From minus 60 degrees to positive 60 degrees among the range of main radiation. The radiation gain of the antenna is greater than 0 dB.Above all,the antenna has high application value on multimode satellite system.