Recently, the authors proposed a fast high-resolution imaging algorithm, called frequency-wavenumber (F-K) Kirchhoff migration. It was developed by combining three algorithms: F-K migration, Kirchhoff migration and inverse boundary scattering transform. The F-K Kirchhoff migration is considered promising in improving the image resolution of images taken with airport security body scanners for which costs can be mitigated by introducing sparse arrays. We investigate the imaging performance of the F-K Kirchhoff migration using ultra-wideband radar with such sparse arrays.