| 摘要 |
A wide-band antenna is intended to enable operation in the transmitting or receiving mode between 30 MHz and 1 to 2 MHz. This antenna principally comprises a radiating vertical mast 1 of a height of some ten metres which provides a vertically polarised radiation throughout the frequency band, a conductive spiral 2 secured on to the guy lines 3,4,5,6 securing the mast and a conductor 7. The spiral which is connected in series between the radiating mast and the conductor forms a choke or impedance coil for the high part of the frequency range and an antenna having a circular horizontal polarisation for the low part of the range. The conductor, which has resistor R inserted in it, connects the spiral to the ground, the resistor being intended to absorb the reflections at the low frequencies of the range. The radiating mast may comprise a steel member or a conductive spiral on an insulating member (Fig. 3). <IMAGE> |
