| 摘要 |
PURPOSE:To eliminate the level reduction of the received signal in the transition process of directivity, by giving an automatic decision to the transiting direction of directivity in which the level of the received signal increases for the variable directional antenna and then giving the transition control. CONSTITUTION:The signal is recived at 22 via variable directional antenna 10 which can transit in the transiting directions of different states of directivity. The directivity of antenna 10 is changed in a minute amount and periodically by sensing signal generator 20, and the transiting direction of the state of directivity in which the level of the received signal increases is decided by phase comparator 24 and based on the changing state of the received signal of receiver 22 which is caused by the variation of the directivity. And this transiting direction is detected by level detector 23 when the level of the received signal of receiver 22 lowers less than the prescribed threshold level, and then transited to the transisting direction in which the state of directivity is decided for antenna 10 in order to give control 25. |
