| 摘要 |
A protected antenna apparatus including an elongated tube; a cable having an upper end with a pair of separate bare leads extending therefrom, a lower end with a connector secured thereto, and an intermediate portion extended between the ends; a twin-lead transmission line having a central axis, a free upper end, a lower end with the bare leads extending therefrom and interconnected together, an intermediate location therebetween wherein each lead is connected with one of the bare leads of the cable, and a notch formed on an upper extent of the line at a location between the intermediate location and the upper end to thereby divide one of the leads into two different pieces and thus create a J-pole antenna having a short leg, a long leg, and an impedance matching stub portion therebetween, and wherein the antenna transmits radio signals of a characteristic frequency as a function of the lengths of the legs and the stub portion; and a coupling mechanism for securing the antenna within the tube and along a longitudinal extent thereof.
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