关于理想导电地上单极子天线的问题

前提是设置了理想导电地：
1、关于单极子天线的馈电：我直接将端口设在极子一端segment——〉start，有错吗?
2、如果端口设置正确，在离地距离很近（远小于波长的位置）上，水平放置的单极子天线，根据镜像原理应该不辐射能量吧?为什么仿真结果增益很大?

課本範例 7 A monopole antenna on a finite ground plane
Keywords: monopole, finite ground, radiation pattern, far field, current
A quarter wave monopole antenna on a finite circular ground plane is constructed and simulated. The circular ground has a circumference of three wavelengths, and the wire has a radius of 1 × 10−5 of a wavelength. The free space wavelength is chosen as 4 m (approximately 74 MHz).