| 摘要 |
A multiple frequency band antenna includes a dipole antenna (4a), which is formed of two dipole antenna elements (8a, 10a). Two extension elements (24a, 26a) extend outward from respective ones of opposed outer ends of the dipole antenna (4a). The length of the dipole antenna (4a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the UHF band, and the sum of the lengths of the dipole antenna (4a) and the extension elements (24a, 26a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the VHF band. PIN diodes (28a, 34a) are connected between the respective extension elements (24a, 26a) and the respective outer ends of the dipole antenna (4a). When a radio wave in the UHF band is to be received, a control unit (180) places the diodes (28a, 34a) selectively in a state in which both are opened, a state in which one of the diodes (28a) is closed while the other (34a) is opened, and a state in which the one diode (28a) is opened while the other (34a) is closed.
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