Directive bar-type antenna

Abstract

Disclosed is a directional bar-type antenna which comprising a plurality of bar-shaped antenna elements including a core and a coil wound around the core. The first bar-shaped antenna element is disposed at a position of a mirror image of the second bar-shaped antenna element with respect to the core of the third bar-shaped antenna element. The first and second bar-shaped antenna elements is positioned such that one end of each of the first and second bar-shaped antenna elements is close to the third bar-shaped antenna element, and the other end is far from the third bar-shaped antenna element. In the present invention, a winding direction of the coil of the first bar-shaped antenna element is preferably identical to that of the coil of the second bar-shaped antenna element, and is opposite to that of the coil of the third bar-shaped antenna element. The directional bar-type antenna of present invention can meet a need for providing asymmetrical directionality in a forward-rearward direction of an antenna for use in a specific system, such as a keyless entry system, and solve a problem in terms of cost and external appearance, in a technique of partially surrounding a bar-type antenna by a shielding member, in view of difficulty in freely controlling directionality of an antenna in an induced electromagnetic field domain, and a need to allow the bar-type antenna to have a difference between respective receiving sensitivities in forward and rearward directions in the induced electromagnetic field domain (while facilitating a reduction in size and cost).

Dependencies are inferred from the claim text.