由四个半波振子组成的垂直直线阵的增益约为8dB，一侧加有反射板的四元式直线阵，其增益约为()dB，即常规板状天线，也就是所说的低增益天线。
14～17
暂无解析
Thetwinshadbeenawayforsuchalongtimethatmanypeopleinthevillagethoughtthey________.
is,are,was,were,itself,himself,themselvesThetradeunion________believedtoregard________asanorganizationwherethemolestedcouldseekadviceandhelp.