| 摘要 |
<p>IMPROVEMENTS IN DOPPLER VOR BEACONS A Doppler VOR beacon comprising a central antenna modulated with a reference wave and a ring of omnidirectional antennas radiating sidebands of a sub-carrier amplitude modulation of the carrier commutated around the ring of antennas to simulate a rotating source, in which the central antenna in comparison with the ring antennas has a higher gain towards the horizon and over a predetermined angle above the horizon. The central antenna may comprise a vertically stacked array, the elements of which may be Alford loops.</p> |
