面向低轨卫星的双圆极化宽带宽角扫描阵列研究

Research on dual circularly-polarized wideband wide-beam scanning array for low-orbit satellites

随着卫星通信技术的日益成熟,相控阵天线被广泛应用于低轨卫星系统,提出了一种面向低轨卫星通信的新型双圆极化宽带宽角扫描阵列天线。阵列天线单元采用一种金属栅格加载的对称阵子,其工作宽带为17 GHz~21 GHz,相对带宽超过21%,同时金属栅格加载方法可有效展宽对称阵子波束宽度,从而在工作频段内使E面和H面波束宽度均超过140°。通过上述宽带宽波束对称阵子作为阵列天线单元,形成8×8的64单元阵面。然后,阵列天线单元经过旋转组阵,实现了双圆极化特性。由于天线单元具有宽带、宽波束性能,有效拓展了阵列波束扫描角度,即在不同旋向下,均能实现二维±60°的波束扫描。阵列在低频17 GHz工作时,法向波束增益为18.2 dB,当扫描离轴角为60°时,增益下降2.8 dB,轴比小于2 dB。在高频21 GHz时,法向增益为19.6 dB,当扫描离轴角为60°时,增益下降3.7 dB,轴比小于3 dB,具备良好的宽带宽角覆盖性能,从而在低轨卫星通信中具有广阔的应用前景。

With the increasing maturity of satellite communication,the phased array antennas are widely used in low-earth satellite systems.This paper has proposed a new dual circularly-polarized(CP)wideband and wide-beam scanning array for low-orbit satellite communication.Initially,the array element adopts a metal grid-loaded dipole antenna,thus increasing its working bandwidth of about 17 GHz~21 GHz(21%).Meanwhile,the grid-loaded metal contributes to widen the half-power beamwidths(HPBW)of the element,which simultaneously increases the E-and H-plane HPBW to above 140°.Next,the grid-loaded dipoles are employed to form up the 8×8 array.After that,the array element is rotated to realize the double CP performance.Owing to the wideband and wide-HPBW of the CP element,the beam scanning angle of the array is effectively expanded to above±60°in two-dimensional.Finally,as the array is working in the lower band of 17 GHz,the broadside gain reaches to about 18.2 dB.When the scanning angle is about 60°,the gain reduction is only about 2.8 dB and the axial ratio keeps of less than 2 dB.As the array is working in the higher frequency of 21 GHz,the broadside gain is maintained of about 19.6 dB.When the scanning angle is about 60°,the gain reduction is about 3.7 dB and the axial ratio keeps of less than 3 dB.As such,the designed array has the attractive wideband and wide-beam scanning performance,thus can be well applied in low-orbit satellite communications.