A smart antenna, an antenna feeder system, an antenna communications system, and an Access Point (AP) are provided. The smart antenna includes an antenna element array and an impedance transformation circuit. A feeding end of the antenna element array is connected to a first end of the impedance transformation circuit, a second end of the impedance transformation circuit is an input end of the smart antenna, and the input end of the smart antenna is connected to a feeder. The antenna element array can form a plurality of different beam shapes, and the impedance transformation circuit is configured to transform the different input impedance of the feeding end of the antenna element array into preset input impedance at the input end of the smart antenna.