| 摘要 |
PURPOSE:To increase a diversity effect by switching antenna elements wherein directivity in horizontal planes is valued highly and antenna elements wherein sensitivity in horizontal planes is valued highly in the best state. CONSTITUTION:An attenuation controlling circuit 23 compares an input signal level with a preset reference voltage to decided on whether the input signal level is high or low, and attenuators 10 and 11 are interposed between a changeover switch and antennas 2 and 3 whose reception sensitivity is valued highly at an intense-electric-field place where an SN ratio is not so important. Therefore, antennas 1 and 4 having highly valued directivity in horizontal planes and said antennas 2 and 3 do not have a great difference and the probability that the directivity-valued antennas 1 and 4 useful for the removal of a ghost are switched is increased. When electric field intensity is low, on the other hand, said attenuators 10 and 11 are not added, so the probability that the sensitivity- valued antennas 2 and 3 are selected is increased. |
