An antenna includes a substrate, and an array of dipole antenna elements on the substrate. A first electronic device controls a baseboard management controller of the second electronic device to return parameter values, the returned parameter values including temperature values of the second electronic device, and actual speed values of a fan of the second electronic device. The limiting rate selection module selects a limiting rate based on the pressure rate value. Thus, alter the mounting of the sensor unit, the receiver unit receives the modification information, and the adjustment unit adjusts the load signal supplied from the sensor based on the modification information. The outside of the shoulder has a wall extending above the shoulder to form an annular recess at the engagement end.