| 摘要 |
PROBLEM TO BE SOLVED: To provide an antenna with which portable radio equipment can obtain a satisfactory polarization characteristic in either use state of a voice communication mode (actual speech communication mode in which a user holds the portable radio equipment near the head and performs communication) or a data communication mode. SOLUTION: One or a plurality of switching means 6 for switching electrical connection states are provided on an antenna element 1 in which an electrical length is about one wavelength in an operation frequency, and the main polarization characteristic of the antenna can be switched to horizontal polarization/ vertical polarization by switching the switching means 6 with the control of a switch control circuit part 8 for performing switching control of the means 6. The switch control circuit part 8 is provided with a means for discriminating the communication media of voice communication/data communication and a means for discriminating the existence/absence of the connection of an external device to the portable radio equipment. It is possible to automatically switch to an antenna having a satisfactory plane of polarization by switching the switching means 6 on the basis of discrimination results of these discriminating means without the user being aware of it.
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