Calibration and test of an active conformal phased array

A free-space calibration technique has been developed for testing active conformal phased arrays. The method is applicable to both receive and transmit operation. The key to the technique is to be able to turn on one T/R (transmit/receive) module at a time while all others are switched off and all radiators are connected to loads internal to the T/R module. This enables the insertion amplitude and phase to be determined and adjusted in the mutual coupling environment of neighboring radiators; i.e., the actual embedded element pattern is present. By using the digital phase shifters in the module, the phase front of the array is collimated. Also, if the module has amplitude control, the desired aperture illumination distribution can be realized. Details of phase and amplitude calibration are described.<>