Patent ID: 6816122
Filing Date: 2004-11-09
Classification: H01Q

Abstract:
An electromagnetic coupling type four-point feeding loop antenna comprising:a tubular body formed by rounding a flexible insulator film member around a central axis in a tubular fashion, said tubular body having a peripheral surface; a loop portion made of a conductor, said loop portion being formed on said tubular body along said peripheral surface around said central axis in a loop fashion, said loop portion having a loop width; four feeders formed on the peripheral surface of said tubular body to feed to said loop portion at four points, each of said four feeders having a feeder width; and four electromagnetic coupling wires, connected to said loop portion, extending on said flexible insulator film member from said loop portion along said four feeders with gaps left between said four feeders and said four electromagnetic coupling wires, respectively, each of said four electromagnetic coupling wires having a coupling wire width, wherein said loop width, said feeder width, and said coupling wire width are substantially equal to one another and each of said gaps is laid in a range between 0.2 mm and 0.8 mm, both inclusive, when said electromagnetic coupling type four-point feeding loop antenna has a feeding impedance of a range between 25 &OHgr; and 100 &OHgr;, both inclusive.