A reduction method of quantization error of excitation coefficient for phased array antenna

Phased array antennas (PAA) enable to form a main beam in the direction of a desired signal and nulls in the direction of interference signals by adjusting excitation coefficient (amplitude and phase) of each antenna element. One method to form nulls in the direction of interference is sidelobe canceller [1]. The signals received by the auxiliary antennas are adjusted to be the conjugate of the interference signal received by the main antenna. The adjusted signals are combined with the signal received by the main antenna. One method to conjugate the signals is the analog beam forming (ABF) using variable attenuator and digital phase shifter. ABF has a large quantization error when antenna elements are few. The quantization error causes the null to shift, so the interference signal is not fully suppressed. Therefore, to form null in antenna pattern, highly precise ABF is required.