地网对VHF天线性能影响的分析研究

Simulation of the Influence of Ground Screen Parameters on Antenna Radiation Performance in VHF Band

基于VHF频段射电天文干涉阵列的天线,研究地网以及不同环境对天线辐射特性包括增益、方向图、谐振点等参数的影响。结果表明,无地网条件下,天线在干燥土壤和沙地的增益分别是3.06 dB和1.44 dB,且存在明显的旁瓣和后瓣;天线在潮湿土壤和沙地的增益分别是4.33 dB和4.25 dB。增加地网后,天线在干燥土壤和沙地的增益分别是4.87 dB和4.97 dB,潮湿土壤和沙地分别是4.39 dB和4.40 dB,方向图不存在明显的后瓣和旁瓣,谐振点稳定在27.0 MHz和69.5 MHz处,且在此之间的频段上,驻波比均满足银河噪声限制条件。由此可以得出结论:在干燥土壤和沙地上铺设地网时,VHF天线性能最好,噪声最低,这对大规模的VHF天线阵列的基础构建环境选择至关重要。

This paper takes the VHF band radio interference array antenna as an example to study the influences of different grounds on antenna gains,patterns and resonances.The results show that the antenna gains on the dry soil and sand are 3.06dB and1.44dB,and there are obvious side and back lobes in pattern.On the wet soil and sand are 4.33dB and 4.25dB.In four cases,the reflection coefficients at each resonance point are different although there are dual-frequency resonance characteristics.After setting the ground screen,the gains of the antenna on dry soil and sand are increased to 4.87dB and 4.97dB,and the wet soil and sand are 4.39dB and 4.40dB,the patterns do not have obvious side and back lobes,the resonance points are stable at 27.0MHz and 69.5MHz,in this band the standing wave ratio satisfies the galaxy noise-limit condition.It is concluded that the VHF antenna has the best performance when setting ground screen on dry soil and sand.This is important for the selection of the building environment for large-scale VHF antenna arrays.