大型双锥椭圆笼形天线关键参数的影响分析

The effect analysis of key parameters of large biconical-ellipsoid cage antenna

基于同轴线馈电的并行时域有限差分(finite-difference time-domain,FDTD)方法,研究分析了双指数脉冲源激励的位于地面上的大型双锥椭圆笼形天线的辐射场,给出了天线的椭圆形笼半径、双锥半角、架高及圆心间距等几个关键参数对该天线辐射场的影响.研究表明:椭圆形笼的半径从3.0 m增加到4.5 m时,对位于天线双锥中心正下方及其向天线外侧偏离的测点场的峰值和上升沿几乎没有影响;双锥半角的改变使测试区内测点场的峰值、上升沿和半高宽(full width at half maximum,FWHM)发生变化;天线架高越高,与地面距离相同的水平面上场的分布越均匀;两个笼与地面相交得到的两个圆的圆心间距越大,过双锥中轴线且与地面垂直的剖面上靠近椭圆形笼的测试区边缘的场更均匀;测试区场的FWHM随着激励源FWHM的增加非线性增加.

The radiation field of large biconical-ellipsoid cage antenna on ground and excited by a doubleexponential pulse is studied and analyzed based on parallel finite-difference time-domain(FDTD)method with coaxial feed.The influence of several key parameters such as the cage radius,bicone half angle,the height of the antenna and the length of the antenna etc on the radiated electric field of the antenna is presented.Numerical results show that there is very little effect on the peak-value and rise-time of the radiated fields of testing points directly under the bicone center and the points along sideward departure from those points as the radius of the cage increases from 3.0 m to 4.5 m;the peak-value,rise-time and full width at half maximum(FWHM)of testing points may be affected by the bicone half angle;the field distribution uniformity on the horizontal plane with the same distance from ground is better as the height of the antenna increases;the field distribution uniformity of the edge region near the ellipsoid cage of the testing area on the plane including the central axis and perpendicular to the ground is better,as the distance between the two centers of the two circles got by the connection of two cages and the ground increases;there’s no linear increase for FWHM of testing fields as the source FWHM increases.