| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a dual system radio communication apparatus which is miniaturized to reduce the cost by simplifying its circuit constitution. <P>SOLUTION: A first and second local oscillators 3, 4 are selectively connected to a transmitting mixer 5 and a receiving mixer 6, using a change-over switch 7. The mixers 5, 6 are connected to an antenna 11 through band-rejection filters 9, 14. The oscillation frequencies F<SB>LO1</SB>, F<SB>LO2</SB>of a first and a second local oscillation signals LO1, LO2 are set to the sum and the difference of the frequencies F<SB>RF1</SB>, F<SB>RF2</SB>of a first and a second radio frequency signals RF1, RF2 and the frequency F<SB>IF</SB>of an intermediate frequency signal IF, respectively. The band-rejection filters 9, 14 are used to pass the first and the second radio frequency signals RF1, RF2 and cut off the first and the second local oscillation signals LO1, LO2, thus simplifying the circuit constitution. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
