| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a radio transmitter-receiver capable of obtaining sufficient transmission / reception performance while corresponding to two frequencies without the need for increasing the number of antennas. <P>SOLUTION: A first antenna 1 and a transmission / reception circuit 3 are provided for communication of 800 MHz, and a second antenna 2 and a transmission / reception circuit 4 are provided for communication of 2 GHz. In the case of the EV-DO communication for the 800 MHz band, switches 9 to 13 are switched to use the first antenna 1 for a main antenna shared for transmission / reception and the second antenna 2 for a sub antenna exclusively for reception. Since the first antenna 1 being the main antenna is the antenna for 800 MHz, no gain is deteriorated, since the second antenna 2 is the antenna for 2 GHz, the sensitivity of the antenna for signals with 800 MHz is low on the other hand. However, the presence of the sub antenna can provide expectation of the diversity. In the case of the EV-DO communication for 2 GHz band, the second antenna 2 is used for the main antenna and the first antenna 1 is used for the sub antenna. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
