An antenna calibration system for a phased array antenna in accordance with one embodiment of the present disclosure generally includes: a beamformer lattice including at least first and second beamformers, each corresponding to a subset of antenna cells, and each including a calibration section for comparing a reference signal to a non-reference signal; and a calibration antenna within the subset of antenna cells corresponding with the first beamformer, wherein the calibration antenna is configured to deliver a first reference signal (mTx) from the first beamformer to be received by a first operating antenna for comparison with a first non-reference signal (Rx) in the first beamformer or in the second beamfomer, and/or wherein the calibration antenna is configured to deliver a second non-reference signal (Tx) from a second operating antenna for comparison with a second reference signal (mRx) in the first beamformer or in the second beamformer.