| 摘要 |
PROBLEM TO BE SOLVED: To provide an antenna unit which is small in size, light in weight and low in cost without causing hindrance to an antenna operation while protecting a circuit board and reinforcing a radiation conductor plate. SOLUTION: The antenna unit 1 is provided with: a circuit board 3 having a ground conductor 4 and to which an antenna circuit 2 is arranged; a sheet-metal made frame 8 having a support 8a and containing the circuit board 3; a sheet-metal made radiation conductor plate 5 arranged on the circuit board 3 at a prescribed interval; a fitting part 6 provided to four corners of the radiation conductor plate 5 and fitted to the support part 8a; and a feeding pin 7 connected to nearly the middle of the radiation conductor plate 5. Further, in order to prevent the fitting part 6 acting like a short circuit part from having an adverse effect onto the antenna operation, a slit 5a an interval with respect to a feeding point P of which is selected to be aboutλ/4 (whereinλis a resonance length) is provided in the vicinity of each fitting part 6 of the radiation conductor plate 5, and a path length of a current from a middle Q at an edge of the slit 5a toward the feeding point P up to the fitting part 6 in the vicinity is selected to be aboutλ/4. COPYRIGHT: (C)2005,JPO&NCIPI
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