定向天线的前后比是指主瓣的最大辐射方向(规定为0°)的功率通量密度与相反方向附近(规定为180°±20°范围内)的最大功率通量密度之比值。它表明了天线对后瓣抑制的好坏。前后比越大,天线的后向辐射(或接收)越小。
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高增益和较大的前后比使UHF信号被极好地接收。
High gain and excellent front-o-back ratio so that UHF can be received consistently.
基于端射阵理论,优化设计了一副小型宽带、具有大前后比的双鞭天线,并以此作为阵列天线的基本单元组成六元均匀线阵。
Then, based on the end-fire array theory, a small broadband twin-whip antenna with big forward to backward ratio is designed.
根据人口统计局的人口计量仪测算,在10月17日或此日前后,美国的人口数将突破3亿,与1967年时的2亿相比,更上一层。
On or around October 17th, according to the Census Bureau's population clock, the number of people in the country will hit 300m, up from 200m in 1967.
the show or the game or whatever else is going on next to the advertisement.
比广告前后的表演或者球赛或者什么广告之外的别的节目有意思。
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