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一、前言在短波段远距离通信时,往往使用对称双极天线。这种天线产生水平极化波,主要用于天波传播,方向性较强,通信距离较远。其有效辐射部分为水平的对称振子,对称振子由多股细长导线构成。双极天线的馈线有平行线馈线和电缆馈线两种。电缆馈电双极天线的对称振子长度往往随使用频率而改变,例如英国TRA-931电台,法国LMT-3451电台均使用这种长度可变的双极天线。我国以前用得比较多的双极天线是固定长度、平行线馈电的双极天线,例如44米双极天线。
I. Introduction In the short-range long-distance communications, often use the symmetrical dipole antenna. This antenna produces horizontal polarized waves, mainly for sky-wave propagation, strong directivity, communication distance. The effective part of the radiation for the horizontal symmetrical oscillator, the symmetrical oscillator consists of multiple slender wires. Bipolar antenna feeder with parallel line feeder and cable feeder two. The length of the symmetrical dipole of a cable-fed dipole antenna often varies with the frequency of use. For example, the variable length dipole antenna is used in the UK TRA-931 radio station and the French LMT-3451 radio station. Bipolar antennas used more in our country are fixed-length, parallel-fed bipolar antennas, such as 44-meter bipolar antennas.