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图一第一列：长线天线的长度（米），第二列用英尺表示的长度(1 feet=0.3048米)，其它为各波段时驻波比。

可见，第一选择为红色行：37.8米。第二选择为蓝色行16米。

图二图三为9:1的商品巴伦。

长线天线的驻波比与线长有关。swr（驻波比）随着地形、线的方向、地面条件、地网而变化。为了得到最好的效果，使用图一列表里适合你安装条件的最长的线。如果长线呈倒L形，会改变长线天线的馈点阻抗和调谐，限制了可用波段（某些波段驻波比高）。红色行是用于短波段最合适的长度。

试着用三种方式安装长线天线。第一种是巴伦的一端接长线天线，另一端接地。第二种是巴伦另一端接4.6~9.2米长的一根地网，第三种方式是不接巴伦，这种方式使同轴馈线的外皮成为地网，这时最好有9米长以上的馈线。

typical swr relative to wire lengths. swr will vary based on topography, wire orientation and use of ground or counterpoise. for best results, use the longest wireshown on the table that will fit your installation constraints. installing your wire as an inverted l will change the feed point impedance and tuning of the wire thereby limiting bands available. rows in color are best overall lengths to use for complete hf spectrum coverage.try installing the unun three different ways. one with the negative terminal grounded, another with a counterpoise wire of 15-30 feet minimum and the third with no connection at all. in this last configuration the coax shield will act as the counterpoise but you should have 30+ feet of feedline to try this option.

英文部分信息来自http://www.balundesigns.com/servlet/the-106/9-cln-1-9-dsh-1-unun/detail，可信度你定。点击翻书的图标就可看到PDF文档，也就是这个：http://www.balundesigns.com/content/Wire%20Lengths%20for%204%20and%209-1%20ununs.pdf