| 摘要 |
PURPOSE:To increase diversity effects by detecting that the receiving signal level of a large-gain antenna is lower than a previously set prescribed value and reducing the gain diference between this antenna and a small-gain antenna. CONSTITUTION:The micro wave received by antennas 1 and 2 is branched and is applied to detecting diodes 3 and 4 to take out DC signals which are proportional to respective input levels, and the difference signal is applied by differential amplifier 5. When the level difference between two input signals becomes lower than a previously set value, discrimination circuit 6 generates a control signal, and this signal is applied to variable attenuator 7 to attenuate the level of the signal in the large- caliber antenna side by a prescribed value. As a result, when the receiving level of the large caliber side becomes lower than that of the small caliber side by a prescribed value, influences of interference signals of the large-caliber antenna side can be eliminated, and diversity effects are increased. |
