Amplitude and phase errors prevent array channels from adding with their intended complex weights, which changes boresight or scan direction, coherent gain, sidelobe level, beam shape and null depth. The impact depends on where errors occur across the aperture, whether they are correlated, the commanded beam, element pattern, frequency and calibration strategy. A single typical channel value does not establish array performance.
Build an error budget for manufacturing spread, temperature gradient, frequency slope, control quantization, LO/clock skew, mutual coupling, power-dependent drift and calibration residual. Use the same RMS, worst-case or statistical assumptions in hardware requirements and the pattern simulation. Specify gain/phase range, resolution, monotonicity, settling and repeatability at the calibrated reference plane.
Reject the requirement if it gives only room-temperature center-frequency accuracy, if the control range is consumed by nominal correction, or if the calibration system cannot observe a failed or drifting channel. Production evidence should retain per-channel raw data before and after calibration plus selected array patterns at band edges, scan extremes, temperature corners and representative fault states.