A millimeter-wave phase array system may include massive heterodyne transceivers as its building elements. A transceiver of each element may include an IQ image rejection heterodyne transmitter and a receiver. Each transmitter may include a single DAC, a Tx I channel, and a Tx Q channel. Each receiver may include an Rx I channel, an Rx Q channel, and a single ADC. For Tx IQ image rejection calibration, amplitude and phase offsets are determined, using both the Tx I and Tx Q channels from a first element and using only one of the Rx I or Rx Q channel from a second element. The IQ channel imbalances are compensated using the offsets in analog domain. A similar procedure is used for Rx IQ image rejection calibration with alternated signal path enabling. A frequency response variation of an RF front end is detected with a single path Tx/Rx channel setup.