Synthesis of a Phased Array with Planar Near-Field Techniques Based on Far-Field Measurements of a Sub-Array in a CATR

Phased array antennas are often built from sub-arrays with identical or symmetrical layout. At an early project stage, performance verification measurements of the sub-array are valuable to proof the single module design. However, the characteristics of the final antenna are questionable without further processing. This work presents a concept that is based on far-field measurements of a sub-array in a Compact Antenna Test Range (CATR) in conjunction with planar near-field (PNF) processing to synthesize the entire phased array antenna characteristics. The procedure is explained with an example of a dual linear polarized L-band planar phased array antenna for an airborne synthetic aperture radar application. It is shown that the measured sub-array can be complemented by the synthesized twin to evaluate the characteristics of a final antenna that is not yet available in this form. The resulting performance of the synthesized entire phased array is presented and compared with simulations. The presented post-processing method would be beneficial to characterizing radiation patterns of large phased arrays by measuring only sub-arrays in a limited test-zone with any measurement principle.