A cellular repeater and method of operating a cellular repeater are disclosed. The cellular repeater includes a variable-gain donor antenna adapted to communicate with a base station and a variable-gain server antenna adapted to communicate with a mobile device. A signal from a selected base station selected from one or more available base stations that are available to the cellular repeater is measured at the donor antenna. The gain of the donor antenna is adapted to maximize a signal level of the signal received at the donor antenna from the selected base station. A calibration signal from the server antenna is measured at the donor antenna to determine a radio frequency isolation between the donor antenna and the server antenna. The gain of the server antenna is adapted to maximize the radio frequency isolation between the donor antenna and server antenna.