大气微波遥感辐射计天线指标设计分析

Design and Analysis of Antenna Specifications in Atmospheric Microwave Radiometers

用于被动式大气遥感测量和对流层电波折射误差高精度实时修正的地基微波辐射计,需采用窄波束、高效率和低旁瓣天线。根据微波辐射计天线传递函数和大气辐射测量方程,提出了天线设计中主波束宽度的选择依据,同时还提出了可根据太阳在辐射计工作频段内的射电辐射流量密度指导天线设计,即可根据太阳扫过天线旁瓣时所引起的辐射亮度温度的附加贡献和微波辐射计系统测量精度要求,确定归一化天线功率方向图中最大旁瓣的可允许值。

Ground-based Microwave Radiometers（MWR） are often used for passive atmospheric remote sensing and measurement, or high accuracy, real time error correction of radio wave refraction in troposphere. For such applications, narrow beam, high efficiency and low-sidelobe antennas are required. Based on the antenna transfer function in MWR and the atmospheric radiation measurement equation,the paper presents a set of selection criteria on main lobe width in antenna design,and proposes a method for antenna design that takes into account the solar radiation flux density within the operating frequency bands of MWR. This method determines the allowable maximum sidelobe of normalized antenna radiation pattern on the basis of two factors：one is the additional contribution to the radiance temperature by the sun passing the antenna sidelobes,the other is the requirement on the MWR measuring accuracy.