Noise reducing rod vehicle antenna
AssigneeHarada Industry Co., Ltd.
InventorsJiro Harada, Masaki Shinkawa, Shinichi Saito, Hiroyoshi Kojima
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Abstract
A rod-shaped vehicle antenna according to the present invention, includes a rod-shaped antenna element having small- and large-diameter portions arranged alternately at regular pitches along the longitudinal direction of a rod-shaped conductor. When the outside diameter of each of the small-diameter portions is D1, that of each of the large-diameter portions is D2, and the pitch (length of each of the small- and large-diameter portions) is P, P is set within the following range: (D2.times.6).ltoreq.P.ltoreq.(D2.times.7). The ratio of D1 to D2, that is, D1/D2 is set within the following range: 0.7.ltoreq.(D1/D2).ltoreq.0.85.
Claims2
A rod vehicle antenna including a rod antenna element having small-diameter portions and large-diameter portions arranged alternately at regular pitches along a longitudinal direction of a rod conductor,
- wherein when an outside diameter of each of the small-diameter portions is D1, a length thereof is P1, an outside diameter of each of the large-diameter portions is D2, and a length thereof is P2, P1 and P2 are set within a following range:
- (D2.times.6).ltoreq.P1.ltoreq.(D2.times.7)
- (D2.times.6).ltoreq.P2.ltoreq.(D2.times.7);
- a ratio Q of P1 to P2 (P1/P2) or P2 to P1 (P2/P1) falls within a following range:
- (1/3).ltoreq.Q.ltoreq.1;
- a ratio of D1 to D2 (D1/D2) is set as follows:
- (D1/D2).ltoreq.0.75;
- and
- wherein the rod antenna element has an area where the small-diameter portions and the large-diameter portions are formed, and a length of the area is 2/3 or more of a whole length of the rod antenna element.
Dependencies are inferred from the claim text.