| 摘要 |
An adjustable helical antenna in which the length and pitch of the antenna may be varied whilst the radius is kept substantially constant. Ends of the wires (23a-d) may be secured to first and second carriages (15a, 15b) which may be moved together or apart by rotating radome (14). To maintain the radious of the helix substantially constant the first and second carriages (15a, 15b) are relatively rotated by threaded sections (12a, 12b) as they move together or apart. The wires (23a-d) are preferably fed at central voltage maxima and the antenna is preferably a multifilar helical antenna. |
