An echo-canceling unit for a simultaneous transmit and receive (STR) system includes at least three phase shifters instead of just two phase shifters in order to provide immunity to phase and/or amplitude imbalances. Each respective phase shifter is coupled to a transmit signal to generate an output signal comprising a selected phase shift with respect to the transmit signal. A weight calculation unit generates a corresponding amplitude-weight signal for the output signal of the phase shifter. A variable attenuator attenuates the output signal of each respective phase shifter based on the corresponding amplitude-weight signal to form an echo-cancelation signal component corresponding to the phase shifter. A first summer then sums the respective echo-cancelation signal components into a received signal containing an echo signal to form an echo-canceled signal. In some embodiments, an information handling system includes a receiver and a transmitter coupled to the echo-canceling unit.