| 摘要 |
An array antenna includes a radiating element (6) for transmitting and receiving radio signals and at least one parasitic element (7) arranged a predetermined distance (d) away from the radiating element (6) and incapable of transmitting or receiving radio signals. The parasitic element (7) is connected with a variable-reactance element (23). A controller (100) changes the directivity of the array antenna by changing the reactance Xn of the variable-reactance element (23). The variable-reactance element (23) is a variable-capacitance diode (D, D1), for example, and the controller (100) changes the reverse bias voltage Vb applied to the variable-capacitance diode (D, D1) to change the capacitance of the variable-capacitance diode (D, D1), thus changing the directivity of the array antenna. The array antenna has a low-cost and simplified structure compared to the prior art device, while facilitating directivity control.
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