Anomalous NFR grating lobes and leakage beams: Causes and solutions

For a planar, limited scan phased array with multiple grating lobes in real space, there are several potential sources of additional, anomalous far-field lobes which may be observed upon transformation of near-field measurement data collected during planar near-field scanning. If there is a constant leakage term present in the measurement receiver independent of the probe position, then a single leakage beam may be observed at boresite regardless of the array scan condition. If the planar, rectangular near-field scan raster is conducted in a bidirectional manner, then periodic aperture spatial or thermal imbalances may induce paired lobes. The measurement grid lattice may need to be reduced below the typical half-wavelength value in order to push the extended grating lobe series associated with the sampling period sufficiently far from the far-field angular region of interest.