A calibration circuit board (100, 200, 100', 200', 402) for an antenna, comprising: a first metal layer (101, 201); a first substrate (102, 202) over the first metal layer (101, 201); a second substrate (103, 203) over the first substrate (102, 202); and a plurality of couplers (110, 210), each coupler comprising: a transmission line (111, 211) provided with an input port (111a, 211-1a, 211-2a) and an output port (111b, 211-1b, 211-2b) at respective ends thereof; and a coupling line (112, 212) coupled with the transmission line (111, 211) and including two first portions (112a, 112c, 212a, 212c, 212c, 212e) respectively located at both sides of the transmission line (111, 211), as viewed from a direction perpendicular to the calibration circuit board, and a second portion (112b, 212b, 212d) connected between the two first portions, wherein the coupling lines (112, 212) of the plurality of couplers (110, 210) are connected in series to provide a first calibration port and a second calibration port, wherein one of the transmission lines (111, 211) and the coupling lines (112, 212) of the plurality of couplers (110, 210) is between the first substrate (102, 202) and the second substrate (103, 203), and the other of the transmission lines (111, 211) and the coupling lines (112, 212) of the plurality of couplers (110, 210) is over the second substrate (103, 203). a first metal layer (101, 201); a first substrate (102, 202) over the first metal layer (101, 201); a second substrate (103, 203) over the first substrate (102, 202); and a plurality of couplers (110, 210), each coupler comprising: a transmission line (111, 211) provided with an input port (111a, 211-1a, 211-2a) and an output port (111b, 211-1b, 211-2b) at respective ends thereof; and a coupling line (112, 212) coupled with the transmission line (111, 211) and including two first portions (112a, 112c, 212a, 212c, 212c, 212e) respectively located at both sides of the transmission line (111, 211), as viewed from a direction perpendicular to the calibration circuit board, and a second portion (112b, 212b, 212d) connected between the two first portions, wherein the coupling lines (112, 212) of the plurality of couplers (110, 210) are connected in series to provide a first calibration port and a second calibration port, wherein one of the transmission lines (111, 211) and the coupling lines (112, 212) of the plurality of couplers (110, 210) is between the first substrate (102, 202) and the second substrate (103, 203), and the other of the transmission lines (111, 211) and the coupling lines (112, 212) of the plurality of couplers (110, 210) is over the second substrate (103, 203). a transmission line (111, 211) provided with an input port (111a, 211-1a, 211-2a) and an output port (111b, 211-1b, 211-2b) at respective ends thereof; and a coupling line (112, 212) coupled with the transmission line (111, 211) and including two first portions (112a, 112c, 212a, 212c, 212c, 212e) respectively located at both sides of the transmission line (111, 211), as viewed from a direction perpendicular to the calibration circuit board, and a second portion (112b, 212b, 212d) connected between the two first portions, wherein the coupling lines (112, 212) of the plurality of couplers (110, 210) are connected in series to provide a first calibration port and a second calibration port, wherein one of the transmission lines (111, 211) and the coupling lines (112, 212) of the plurality of couplers (110, 210) is between the first substrate (102, 202) and the second substrate (103, 203), and the other of the transmission lines (111, 211) and the coupling lines (112, 212) of the plurality of couplers (110, 210) is over the second substrate (103, 203).