VOR type antenna for helicopter - has high magnetic permeability shielding to protect antenna from interference caused by rotors

摘要

The aerial has a U-shaped element formed by equal lengths of coaxial cable (6) and a hollow cylindrical tube (8) interconnected by an insulator block (7). A protective tube (9) coaxially surrounds the element to provide a magnetic screen for perturbations created by the blades of a helicopter on which the aerial is mounted. The tube material has a high magnetic permeability. The coaxial cable and tube are maintained in position at their ends adjacent the insulator block by respective metal rings (92,94) and the cable inner conductor is continued through the insulator block and is soldered to the tube via a conductor plate (62) soldered in the tube end. The two metal rings serve to short-circuit the outer conductor layers of the cable and tube to the protective tube.