偏焦偏置抛物面天线的辐射特性

Radiation of the Offset-Fed Parabolic Antenna

以馈源横向偏焦量Δy作为变化因素分析了偏焦偏置抛物面天线的远场辐射特性。在采用坐标转换、相位计算的基础上运用口径场法推导了远区电场的近似表达式 ,并对不同偏焦量Δy下的天线方向图进行了计算和比较分析。结果表明 ,随着偏焦量Δy的增大 ,天线主波瓣偏离抛物面的焦轴线角度越大 ,天线增益越小 ;而且主波瓣宽度越宽 ,旁瓣的不对称性越明显 ,第一旁瓣的相对强度也越大。

The radiation of the offset-fed parabolic antenna i s analyzed using Δy as a factor. Using aperture field method, the electric field expression is derived based on coordinate transformation and phase computation. The radiation pattern of the offset-fed parabolic antenna is computed and analy zed with variation of Δy. Computed results indicate that the more Δy is,the la rger the angle of antenna mainlobe from the axis is,and the less the antenna gai n is;at the same time,the more the mainlobe width is,the more clear the dissymme try of antenna sidelobes becomes,and the larger the first sidelobe is.