| 摘要 |
PROBLEM TO BE SOLVED: To receive radio waves, while avoiding the effect of current flowing though a circuit board by providing a 2nd antenna at a position where currents flowing to a conductive substrate cancel each other. SOLUTION: A whip antenna 2 is provided at an edge part of a circuit board 1. A built-in antenna 3 is provided around the center of the board 1 in a lateral direction and is provided linear symmetrically, with respect to the center axis in the short side direction of the board 1. The whip antenna 2 extends vertically and receives vertically polarized waves. The built-in antenna 3 extends horizontally and receives horizontally polarized waves. The antenna 3 divides a current, that flows to the board 1, into two parts. That is, a 1st part current and a 2nd part current flow in the opposite directions from each other. As a result, the effect of the 1st part current on the antenna 3 and the effect of the 2nd part current on the antenna 3 cancel each other.
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