星载高增益毫米波SAR相控天线阵设计

Design of Spaceborne High Gain Millimeter Wave SAR Phased Antenna Array

介绍了一种高增益、高效率的星载毫米波合成孔径雷达(SAR)有源相控天线阵的设计。天线单元采用了窄边开缝的波导缝隙天线,辐射缝隙与波导宽边垂直,天线具有效率高、匹配良好的特点。在方位向,波导缝隙天线组成直线阵,直线阵内采用折叠的波导功分器降低了直线阵的剖面高度。在距离向,波导缝隙直线阵紧密排布,形成一维相扫阵列。定标网络及馈电网络均采用波导形式并集成于天线阵列背面,其中,定标网络通过定向耦合器改善了定标通道的一致性及带内起伏特性,馈电网络通过魔T结构改善各有源通道间的隔离度。以距离向84个直线阵为一个子阵列,最终设计的天线全阵在方位向共包含8个子阵列,总体尺寸是595.8λ_(0)×56λ_(0)(λ_(0)是中心频率在自由空间中的波长)。实测天线带内最高增益为54.37 dBi,辐射效率65.2%。天线阵列具有高增益、高效率的优点,同时结构简洁紧凑,适用于星载毫米波SAR系统。

The design of a spaceborne millimeter wave synthetic aperture radar(SAR)phased antenna array with high grain and high efficiency is introduced.The antennas are narrow wall slotted waveguide ones with high efficiency and good matching capacities,in which the radiation slots are vertical with the waveguide wide edges.In the azimuth direction,the slotted waveguide antennas form a linear array,and a folded waveguide divider is adopted to reduce the profile height of the array.In the range direction,several slotted waveguide linear antenna arrays are closely arranged to form a one-dimensional phase scanning array.The waveguide calibration network and feed network both adopt the waveguide form,and are integrated at the back of the antenna array.The directional coupler is adopted in calibration to improve the channel consistency,and the magic T structure is adopted in the feed network to improve the channel isolation.The whole antenna array contains 8 subarrays,each of which contains 84 linear arrays in the range direction.The total size of the whole array is 595.8λ_(0)×56λ_(0),whereλ_(0) is the wavelength of the central frequency in free space.The measured maximum gain of the antenna in the band is 54.37 dBi,and the radiation efficiency is 65.2%.The antenna array has the advantages of high gain and high efficiency and a simple and compact structure,and is suitable for spaceborne millimeter wave SAR system.