Medium frequencies and horizontal magnetic dipoles (vertical loopantennas) can be used in underground radio communication in mining sections of coal mines.
中频频率和水平磁偶极子天线(垂直环状天线)是井下采区无线通信可使用的频段和天线型式。
2
On the pulse frequency encoding of the antennas, the thesis provided the feedback units using multi closed loop delay circuit.