The disclosed embodiments provide a system that uses a first antenna and a second antenna in a portable electronic device. During operation, the system receives a request to switch from the first antenna to the second antenna to transmit a signal to a cellular receiver. Next, the system loads a set of radio-frequency (RF) calibration values for the second antenna. Finally, the system performs the switch from the first antenna to the second antenna to transmit the signal, wherein the second antenna is operated using the RF calibration values after the switch.