PURPOSE: To vary an antenna gain at a field, to provide portable performance and mobility in common and to attain small size and light weight of the antenna by devising at least one antenna element to be freely removed.

CONSTITUTION: The array antenna system is provided with a grounding conductor 11, a dielectric body 12 formed on the grounding conductor base 11 and patch antenna elements 21a, 21b whose coaxial connector 13 is fitted to a connector 13 provided on the dielectric body. A throughhole plating 14 through which legs of the connector 13 are soldered is connected to the board 11 through the dielectric body 12 via a land with the surface of the dielectric body 12. Then one antenna element 21b is used for a removable gain variable auxiliary antenna element and when the antenna is used for a one-element antenna, a resistive terminator is connected in place of the antenna element 21b and when the antenna is used for a 2-element antenna, the element the same as the antenna element 21a is used for the antenna element 21b.