Overview of calibration process for wideband beamforming network

An Electronically Scanned Array (ESA) Antenna uses Beamforming Network (BFN) to have the ability to form beams for discrete pointing angles, depending on the BFN characteristics. BFN calibration must be ensured in order to enable continuous Beamforming to any selected pointing angle. In addition, the calibration minimizes the squint errors. Moreover, the calibration correct the time delay mismatches that the difference between RF channels create. Taking into account that the BFN is able to control the continuous beam pattern direction, we can also apply a variety of weighting functions (tapering) according to application. The adopted weighting leads, as expected, to a controlled beam pattern and side lobes level. The calibration process is accomplished adaptively, which guarantees an optimal continuous beam pattern and low BFN sensitivity to interference. A BFN system, which is able create continuous pointing angles, has been successfully demonstrated in the laboratory environment.