| 摘要 |
638,020. Aerials ; aerial coupling arrangements. STANDARD TELEPHONES & CABLES, Ltd. June 4, 1947, No. 14769. Convention date, May 15, 1946. [Classes 40 (v) and 40 (vii)] An antenna radiating vertically polarized waves in a uniform horizontal pattern comprises a hollow conductive body of cylindrical shape formed in two parts 1, 2 separated by a gap and energized by a feeder 8, 9 at a point 6 diametrically opposite to a bar 7 shortcircuiting the gap ; a standing voltage wave occurs along the gap which then acts as a transmission line to feed upper and lower groups of vertical quarter-wave radiators 10- 17 in equal and opposite phase relation. Tube 5 conductively joins the two parts at points of low R.F. potential and permits the antenna to be mounted on a conductive mast 18 with minimum current flow into the mast. The line formed by the gap is loaded by compensating reactances presented by the radiators and hollow body, and, over a broad band of frequencies, maintains a constant propagation velocity and match with a 50# feeder. The hollow body may be constructed of solid or perforated sheet metal, a plastic conductively coated or wire netting. An insulating material may seal the gap. An array of such antennas may be stacked vertically on a mast. Typical dimensions for the several parts of the antenna may be as follows : D=.32#, d=.032#, H=.072#, g=.0048#, L=.236#. The cylinder may have a circular, elliptical or square cross section. |
