| 摘要 |
PROBLEM TO BE SOLVED: To provide a radio communication device that can keep communication available, even when a main antenna emitting/capturing a radio wave is faulty. SOLUTION: If a whip antenna (main antenna) is faulty, an impedance as seamed from a transmission circuit 13 toward the whip antenna becomes infinite. When a discrimination circuit 22 that receives a current level from an envelope detection circuit 20 discriminates the current level reaching a threshold or over resulting from the defective whip antenna 8, a control circuit 24 controls a transmission changeover switch 15 to be thrown from a 1st transmission switching state (show in solid lines) into a 2nd transmission switching state (shown in broken lines). A transmission wave outputted from the transmission circuit 13 is not given to the whip antenna 8 but to a flat plate antenna 9 (sub antenna), and the flat plate antenna 9 emits the wave as a radio wave. Thus, even when the whip antenna 8 is faulty, the flat plate antenna 9 can emit/ capture the radio wave.
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