ANTENNA DEVICE AND RADIO RECEIVER USING THE ANTENNA DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive antenna device which is smaller than a loop antenna with better directivity and can omit a matching circuit in a receiving circuit and also a variable frequency circuit is not required following the change in receiving frequency with respect to a device which is primarily used in a free space. SOLUTION: In regard to an antenna device which is used for a radio call receiver, a helical antenna 1 is placed along the side of a circuit substrate 4 where a receiving circuit 3 is mounted. Thus, a helical antenna where the main polarization direction caused by a single antenna 1 is equal to the Z axis direction is constructed together with a dipole antenna where the main polarization direction caused by an antenna 1 and the substrate 4 is equal to the Y axis direction. These two antennas whose main polarization directions are approximately orthogonal to each other compensate the null points of directivity with each other to secure the non-directive characteristic that has high antenna gains in all directions in a free space.