An electronic device comprising: an antenna array (197, 230) including a plurality of antennas; a wireless communication module (192, 220) electrically connected to the antenna array and configured to form directional beams through the antenna array; at least one processor (120, 200) operatively connected to the wireless communication module, and configured to: identify a type of an object based on information received from a user interface or a camera; identify a first beam width based on the identified type of the object; transmit a sequence of first directional beams having the first beam width to scan first regions having a first size through the antenna array, receive a sequence of first reflected waves generated by reflection of the sequence of the first directional beams from the object through the antenna array, transmit a sequence of second directional beams having a second beam width narrower than the first beam width to scan second regions, which are included in the first regions and have a second size smaller than the first size, through the antenna array based on at least a portion of the received sequence of the first reflected waves, receive a sequence of second reflected waves generated by reflection of the sequence of the second directional beams from the object through the antenna array, and authenticate the object based on at least a portion of the sequence of the second reflected waves. an antenna array (197, 230) including a plurality of antennas; a wireless communication module (192, 220) electrically connected to the antenna array and configured to form directional beams through the antenna array; at least one processor (120, 200) operatively connected to the wireless communication module, and configured to: identify a type of an object based on information received from a user interface or a camera; identify a first beam width based on the identified type of the object; transmit a sequence of first directional beams having the first beam width to scan first regions having a first size through the antenna array, receive a sequence of first reflected waves generated by reflection of the sequence of the first directional beams from the object through the antenna array, transmit a sequence of second directional beams having a second beam width narrower than the first beam width to scan second regions, which are included in the first regions and have a second size smaller than the first size, through the antenna array based on at least a portion of the received sequence of the first reflected waves, receive a sequence of second reflected waves generated by reflection of the sequence of the second directional beams from the object through the antenna array, and authenticate the object based on at least a portion of the sequence of the second reflected waves. identify a type of an object based on information received from a user interface or a camera; identify a first beam width based on the identified type of the object; transmit a sequence of first directional beams having the first beam width to scan first regions having a first size through the antenna array, receive a sequence of first reflected waves generated by reflection of the sequence of the first directional beams from the object through the antenna array, transmit a sequence of second directional beams having a second beam width narrower than the first beam width to scan second regions, which are included in the first regions and have a second size smaller than the first size, through the antenna array based on at least a portion of the received sequence of the first reflected waves, receive a sequence of second reflected waves generated by reflection of the sequence of the second directional beams from the object through the antenna array, and authenticate the object based on at least a portion of the sequence of the second reflected waves.