HF doublet antenna

例句：

1. 1. The HF doublet antenna is used for communication between satellites and ground stations.
   双极天线用于卫星与地面站之间的通信。
2. 2. The antenna was designed to receive signals from both the north and south polar regions.
   天线设计用来接收来自南北极区域的信号。
3. 3. The doublet antenna has a unique ability to transmit and receive signals in both directions.
   双极天线具有独特的双向传输和接收信号的能力。