| 摘要 |
A loop antenna unit (36, 36', 70, 70', 72, 72', 74, 74') includes a looped antenna element (52); a first feeding cable (44) that feeds power to a first feeding point (54) on the antenna element; a second feeding cable (48) that feeds power to a second feeding point (56) on the antenna element; and a circuit switching portion (SW1, SW2, SW3, SW4) that disconnects a feeding cable corresponding to an unused feeding point out of the first feeding point and the second feeding point, from the unused feeding point, wherein the feeding cable transmits a signal generated by superposing a high-frequency signal related to communication by the loop antenna unit on a dc signal for control over switching by the circuit switching portion, and wherein the loop antenna unit further includes: a first filter (62, 64) that extracts a high-frequency signal related to communication by the loop antenna unit from a signal supplied through the feeding cable and supplies the extracted high-frequency signal to the antenna element; and a second filter (66, 68) that extracts a dc signal for control over switching by the circuit switching portion from a signal supplied through the feeding cable and supplies the extracted dc signal to the circuit switching portion, the first filter and the second filter being provided for the first feeding cable and for the second feeding cable, respectively.
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