微带天线带宽及模式特性研究

Study on Bandwidth and Mode Characteristics for Microstrip Antenna

微带天线具有剖面低、重量轻、易于与平台共形等优点,传统微带天线带宽较窄,目前已有一些方法来展宽微带天线带宽。然而,设计中发现,展宽微带天线带宽的同时可能会出现高次模,高次模的出现导致天线方向图的恶化,而目前这方面研究还较少。本文基于线极化微带天线模型,对影响天线带宽的因素和天线高次模出现的条件进行了分析,得到以下结论:为了增加天线带宽,应选用小介电常数的介质板,同时增加天线和反射板之间的距离并增加天线宽度;通过对微带天线模式特性进行分析可知,若天线较宽,为了抑制高次模的出现,天线高度h应小于0.15λ_0,随着天线的变窄,这一限制逐渐变小。

Microstrip antenna has the advantages of low profile, light weight and easy to be conformal with the shape of the platform. The bandwidth of traditional mierostrip antenna is narrow, and some methods to broaden the bandwidth of mierostrip antenna have been proposed in recent years. However, high order modes may occur while broadening the bandwidth of the mierostrip antenna, which will lead to the deterioration of the antenna pattern. Based on the model of linearly-polarized microstrip antenna, the factors that impact on the bandwidth of the microstrip antenna and the high order modes have been studied in this paper, the results indicate that： （1） a dielectric plate with small dielectric constant, a larger distance be- tween the antenna and the ground, and a larger width of the antenna should be used to broaden the bandwidth of antenna; （2） for wider width antenna, the height should be less than 0.15A0 to suppress the high order modes, however there are less limitation for narrower width antenna.