| 摘要 |
PROBLEM TO BE SOLVED: To protect a GPS antenna device from radio disturbance caused by a portable telephone set. SOLUTION: A band pass filter 13 which lets the GPS radio wave (575.42±1.023 MHz) pass through is placed in the front stage of a first stage amplifier 14 of the GPS antenna device. Since this allows the front stage of the first stage amplifier 14 to attenuate a radio wave in an unwanted frequency band received by an antenna part 11, the first stage amplifier 14 will not be saturated with the radio wave transmitted by the portable telephone set or the like and pvor reception of received GPS radio wave due to attenuation caused by the saturation of the first amplifier 14 can be prevented.
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