The in-situ calibration of a bilateral space-fed phased array antenna

This report describes an in-situ technique to estimate the following parameters of a phased-array antenna: (1) the relative array-element excitation voltages, (2) the array-element tuning phases, and (3) the RF phase shifts at the array elements. This technique has several significant features. First, it involves the use of two auxiliary antennas. One is a passive antenna mounted close to the phased-array antenna. Its output is used to produce a reference phase for phase measurements. Second, it contains a technique to reduce the errors in phase estimates. Third, it takes note that beam steering uses phase sums of the form (phi k + Beta kl), where phi k is the tuning phase for the k-th array element and Beta kl is an RF phase shift of the array element, and pays special attention to reduce the errors associated with the estimates of these sums. Fourth, it assumes the use of a reasonably stable and strong CW source of commercially available quality. No other assumptions are made.